Blackmailing Big Booty Bridget

My mom was away on a business, leaving me at home alone with my twin sister for the week. Bridget had driven mom to the airport on Monday morning so we could have the car to get to and from school. It was around midnight on the first night of having the house to ourselves and I was on the couch in the living room. I was flipping through the channels and landed on American pie 2. I realized how similar the environment was to our high school. We were both about to finish our senior year, having just turned 18. When the scene with the two girls offer to do lesbian shit for the guys and the other guy, I started to get turned on. I thought the one with the darker hair was fucking hot. Her tits were great. I wasn't sure if they were real but I didn't care if she had fake tits. I wanted to slap them with my now hard dick and cum on her awesome nipples. I pulled out my dick and started to jack off. I paused and rewound to the frame where the blonde was kissing the chest of the dirty slut I wanted to slap with my dick. I was about to cum when the door opened and my caught me in the act.

"Oh my god Evan, what the fuck!?" She shouted at me.

"What the hell, sis! Don't' you knock!" I retorted.

"It's the living room asshole. Everybody uses this room! If you wanna jerk off in peace, go to your bedroom! I'm gonna tell Mom tomorrow that you pay with yourself on her couch!" She threatened.

"You're not gonna do that. In fact, you're gonna help me." I replied.

"Help you? Are you insane!? Why would I help you masturbate? You can clearly do that yourself! Bridget asserted.

"Cos if you don't, I'm gonna tell Mom that you let Mr. Watson cum on your ass to get A's!" This was true. I had caught her 2 weeks ago leaning over the dumpster after school while one of the geography teachers jerked onto her bare ass in exchange for good grades.

"What are you talking about? That's so gross!" She denied. I doubled down on my accusations and threats but she continued to insist I was making it up. That was until I pulled out my phone and showed her the video I took. I kept the video on my phone for a couple reasons; My sister had a big juicy ass and I had jerked off while watching the video several times, plus I knew this would be a handy blackmailing tool. I guess I didn't think I'd get to use it so soon.

"You need to delete that video, you perv!" My sister insisted.

"You need to earn the right to have that video deleted!" I demanded

"Alright fine, you want money?" She offered. I told her I wasn't interested in the money. I made plenty money selling pot to loads of guys at school. Somehow, Bridget didn't know that cos she didn't threaten to tell Mom about it.

"I still got this boner. You need to come over here and blow me while I watch this frame." I instructed. She was grossed out by the demand but realized that I wouldn't delete the video unless she complied. I also told her I had hard copies and would have them distributed round the school. She begrudgingly came over to the couch and took my still hard dick in her hand.

"God dammit, bro. Your dick is huge! I think it's the biggest I've ever seen!" She remarked.

"You like it huh?" I smirked. It was glaringly obvious that she wasn't repelled by my thick 10-inch member.

"Uggh, let's just get this over with." She leaned over me on the couch and took my head in her mouth. As she slowly bobbed up and down, I ran my hand over her ass while I looked over the lesbian frame I'd paused on the TV. I decided I preferred for my eyes to move from the sight of my sister's big ass in the tight blue jeans she was wearing to the big blowjob lips that wrapped round my dick. I didn't have to give her any instruction at all. My sis was a pro! It was the best head I'd ever been given. As I got closer to cumming, I dug my fingers into Bridget's ass cheek and placed my other hand over her head whilst I fucked her face with increasing thrusts. She didn't resist. It seemed like she'd been into it. I told her I was gonna cum and she didn't stop her rhythm. I came in her mouth and she took all of my cum in her mouth. Swallowing every last drop.

"Wow, sis. You must have really enjoyed that." I joked.

"I like to give head and you have a nice dick so if I'm being blackmailed, I might as well make the best of it. You clearly enjoyed it so my work is done here. Now delete that video!"

"Sorry Sis. That was too good to be a one off. This is gonna have to be an on-going arrangement. Tomorrow morning I'm gonna cum on your ass in the shower before we leave for school, then in the car, we're gonna pull over somewhere and you're gonna blow me before classes start. After school's out we're gonna go home and I'm gonna blow my load in your ass."

"Woah woah woah! There's no way you're fucking me, Bro! I can't fit your giant dick in my ass!" Bridget Claimed.

"But where's a better place to for a giant dick to be than inside a giant ass?"

"You're such an asshole!" She laughed.

"Well speaking of assholes, you can tell Mr. Watson he owes me 60 bucks!" I slapped her ass and told her I'd see it in the morning, bright and early.