Sister Dare

Terri and Mona abruptly stopped talking as soon as I stepped onto the deck. When two girls stop talking as soon as you show up, that's never a good sign.

That's Terri my girlfriend and her older sister Mona. They were both stretched out on blankets, soaking up the sun in their bikinis... but I knew Terri had only very faint tan lines around her breasts, so I had a feeling they'd both been topless before they heard my car pull up outside. Mona was a couple of years older than Terri, she'd been in my class through most of high school, and I'd always wondered what her breasts looked like.

Gotta learn to come in more quietly, I told myself.

"What's the smirk all about?" Terri asked. "Naughty thoughts?"

"Well, what were you guys talking about that you stopped so suddenly?" I countered, kicking off my shoes, pulling off my shirt, and lying a blanket out on the ground to join them.

"What's it worth to ya?" Mona asked me. I noticed a couple of empty wine coolers on the ground between them: not enough to get anybody drunk, but enough, especially on a warm day, to make them both pretty mellow.

"Well, that depends on how good it is."

"Oh, knock it off," Terri said to her sister.

"It's really good," Mona said in a stage whisper, giving me a wink.

Whatever it was, Terri obviously didn't want me to hear, so of course I was intrigued. "Okay, what do you want?" I had a feeling she was going to ask me to rub suntan lotion on her back, which I guess Terri would have been okay with.

"Lie down here with us," she said.

"Um... I already am?"

"We're not wearing shorts. Take yours off."

I looked over at Terri. She wasn't sure about this. "It's not as if I haven't seen him in his underwear before," Mona reminded her. Which was true: she'd accidentally walked in on us a couple of times in Terri's room, but fortunately both times we'd only been in the early stages of foreplay.

"Whatever," Terri said.

"Fine," I said, pulling off my shorts. My boxer-briefs had a lot more material than their bikini bottoms, but I had the start of a pretty decent boner to hide. I decided to lay on my front. "Okay, what's the big secret? What were you talking about?"

"Um... you," Terri said.

"Anything interesting?" I asked.

"Terri said you're good in the sack," Mona said.

"Okay, that's enough," Terri told her.

"Girls talk about that?" I asked. And yeah, of course I was pleased.

"Oh yeah, she says you make her cum almost every time."

"Jesus, Mona," Terri said.

"What's wrong? It's not as if he doesn't know. Assuming you're telling the truth. Is she telling the truth? Do you always make her cum first?"

"I guess."

"You either do or you don't. Honestly, I've rarely been with a guy who ever does that, much less always. Maybe I'm a little jealous "

"Maybe you're just frigid," Terri teased.

Mona gave her the finger, accompanied by a rude gesture. "I'll have you know I can cum all over the place, and cum good. Just usually alone, is all."

"TMI," I shouted.

"Well," Mona said, "still sounds like bullshit to me. Or wishful thinking, at least."

"Believe it or don't, I don't care," Terri said, sounding annoyed now.

"Okay, then prove it."

"What do you mean, prove it?"

"Go ahead, fuck my sister," Mona told me.

"No way," I said, at the same time Terri was saying "Not even if you were serious."

Mona sat up and took off her top. "Okay," she said, does this say 'serious' to you?" I tried not to react audibly to the fact that Mona had amazing breasts. I mean I'd suspected as much, because I'd seen her in a bikini and tight shirts in the past, and her younger sister's breasts were pretty damn nice, but... wow. "Come on, let me see."

"Even if we wanted to," Terri said, "I don't think I have any condoms upstairs. Did you bring any with you?" she asked me.

Was she actually considering this, or just naming reasons it wasn't going to happen? "No," I said.

"That's okay," Mona said, "You have to do it without a condom."

"Are you completely crazy?" Terri asked. She wasn't on the Pill, which Mona knew: she wasn't either, because both of them had bad reactions to it.

"You said you cum first, right? Then let him fuck you without a condom and then pull out before he cums."

"That doesn't sound very fair to me, does it?" I asked, still just humoring her along.

"Oh, you'll be okay," Mona said. "I'll suck you off when you're done."

"You will not," Terri snapped.

"Then you can do it. We can worry about that afterward. If he cums in you right away it'll hardly matter."

"He's not going to cum in me."

"Then prove it. I dare you."

They were getting serious. "Terri, this isn't just winning a bet: if I cum in you, you may end up pregnant." Definitely, in fact: I knew her rhythm.

"But you won't. I trust you."

I didn't trust me: between this discussion and Mona's naked tits, I was already halfway to spraying cum all over the patio.

"Then let's get on with it," Mona said, "before you chicken out."

She knew how to press Terri's buttons: "dare"... "chicken out"...

And my buttons? Well, having an excuse to fuck Terri without a condom was a strong temptation.

Mona grabbed her bikini top and ran upstairs to Terri's room, and I grabbed my shorts and we followed. Mona climbed onto the foot of the bed and sat there, cross-legged.

"You need to watch, too?" Terri asked, starting to undress.

"Hell, yeah. I need to make sure you go through with it. Also, I never watched anybody fucking before."

Once Terri was stretched out naked on the bed, I began to slowly stroke her nipples, which were as hard as little pebbles. I wondered whether I could make her cum by just sucking on them - I'd done that once before - but that probably wouldn't satisfy Mona.

I moved my attention down Terri's body until I was lightly stroking her pussy while my tongue was working her clit. Terri was moaning softly. I could tell Mona was squeezing her legs together. "No fair if you make her cum too soon," Mona said.

"He can make me cum whenever he wants to," Terri said softly.

I was already starting to over-think this: yes, if I could get Terri on the verge of cumming before I entered her, that would be best.

But her topless sister, sitting so close to us and clearly aroused, wasn't going to help my self-control any.

If she decided to pull off her bikini bottom and play with her own pussy, I'd probably cum instantly.

Stop, wait, don't even think about that. Get that out of your mind.

"Time to get on with it," Mona said.

I slid my underwear down my legs, and Mona leaned forward slightly as my cock sprang into view. I'd probably never been harder than I was now, getting ready to fuck my hot girlfriend, unprotected, with her hot, topless sister watching. I spread Terri's legs, get into position between them, and slowly eased my cock inside of her.

I'd only ever had sex twice before without a condom, and never with Terri, and I wasn't prepared for how... warm she'd feel. How caressed my cock would feel sliding through her wetness.

"Ohgodfuckinggod," Terri said when I was fully inside her. "I almost came right there."

Problem is, I almost had as well. I could feel my balls tighten, as they thought I was giving them the signal to fill my girlfriend with enough semen to change both of our lives forever.

"Wait," I said, "just hold still for a moment, let me..." My cock remained fully buried into Terri's pussy, but everything seemed to be settling down. Then my cock twitched, involuntarily, and we both thought... but no, everything was okay.

I withdrew slowly, still okay, still hard, and then back in. Terri sighed.

"You can stop now if you want," Mona said. "Don't push your luck anymore. You've proved your point."

"No," I said, withdrawing my cock again, "I'm okay." And I was, full control now. Mona had moved closer to us, paying a lot of attention to my hard, wet cock.

Into Terri's pussy again, harder than before.

I knew this was her first time with an uncovered cock, and she was really enjoying it. I was fucking her in earnest now. From the corner of my eye, I could see Mona touching her own breast.

"H-harder," Terri moaned. "Fuck me harder, I don't care what you have to do, make me cum..."

"Oh..." Mona said.

"Close," Terri said, "Then fuckfuckfuckfuck... oh-yes," and she shivered and came, then went limp under me.

I waited a moment, then carefully pulled out of her.

Mona wasn't playing with her breasts anymore, but I don't she realized how conspicuously she was staring at my cock.

"Okay, I dare you now," Terri said to her after a minute.

"What?"

"Let him make you cum first, like I did."

"Are you craz-?" Mona began, then said "Oh, right, like you'd let me fuck your boyfriend."

"If you're not chicken."

Mona pulled off her bikini bottoms. Unlike her sister, she was cleanly shaved. I'd never been with a girl who was shaved like that and and hard as my cock was, I was suddenly dying to bury my face in her pussy. "Fine, I'll call your bluff. Come on, fuck me good."

I could have just said no, but instead I asked both of them "Are you sure about this?"

"Yes," they both said at once, but I could tell neither of them really was. And why would they be? But neither of them was willing to back down.

I pushed Mona onto her back, spread her legs, and brought my mouth to her pussy. I figured this was safer for several reasons, plus I really liked the idea of licking Mona's smooth pussy.

This was only the second pussy I'd ever eaten, and Mona began responding almost immediately, first sighing softly and then moaning.

Without taking my face away from her pussy, I turned by body around so my cock was almost touching her mouth. I began licking and sucking more aggressively.

All she had to do was let my cock into her mouth for just a moment - even the tip would do - and I'd let myself go and shoot a gallon of cum down her throat. I'd cum, I'd make sure she came, the dares would be over, and we'd get out of this without any eggs being fertilized.

But that would have been too easy. Terri pushed her sister's head away from me and said "Not good enough: you made me take his cock in my pussy, now it's your turn. Chicken?"

"Okay, do it," Mona growled at me. "I'm so close."

So was I - especially since a few seconds earlier I was on the verge of letting myself cum.

"Seriously?" I asked Terri. "You want me to do this?"

"Do it!"

I turned my body around again, and positioned the tip of my penis just at the opening of her vagina. This was enough for me to feel how wet she was.

I held that position for a moment and when nobody to me to stop, pushed deep into my girlfriend's sister's pussy. "Oh my fucking god," she groaned, "yes I needed that."

"Oh yeah," I groaned, "that's so good."

"I can't believe you're really doing this," Terri said.

"Hey, this was your idea," Mona said. And then to me, "Fuck me harder. Please."

"Well, you can stop now," Terri said. "You proved you're not chicken, so just -"

"You're chickening out?" Mona taunted. "You're afraid your boyfriend will cum in me?"

Terri said nothing, so I began fucking Mona harder. She gasped a few times, and I was struck by how differently the sisters sounded when they were aroused. "So close," Mona said breathlessly.

I thought we were home free, until Mona tightened her pelvic muscles around my cock, which felt like it was suddenly being sucked. I groaned loudly, and sent a stream of cum deep inside of her. She came, groaning loudly.

"Oh shit no," Terri said.

I could have pulled out at that point - but the harm was already done, so I kept going, delivering three more loads.