This time we were almost too tired to cuddle afterwards, but I couldn't help but sniff the finger that I'd had up her ass. She giggled and said, "Don't worry, Johnny, I'm usually pretty clean up there, but I'll get something anyway." She got up on shaky legs and, cupping her hand under her cunt, walked out of the bedroom, coming back a minute later with a couple of washcloths, wiping my finger off with one and my cock and balls with the other. We snuggled up to each other and went to sleep almost immediately.
The next morning, I lay awake for a little while, thinking about the irreversable step I'd taken and the secret I now had to keep. I was idly thinking about whether or not I still wanted to date women at school when I suddenly realized that it was the first day of classes. I got up, and my grandmother stirred and said, "Ready to go to class?"
I smiled and said, "I'd better take a shower--I smell like sex from head to toe." She smiled back and said, "Well, why don't you make coffee and I'll get in the bathroom, and you can join me in the shower when the coffee's done; just bring the cups in the bathroom." I put on my shorts (didn't want the neighbors to come to the back door and see me naked, coming to the obvious--and true--conclusion), and made the coffee. I brought the cups into the bathroom where Grandma was already in the shower, and setting the cups down, noticed something next to the toilet that it took me a while to recognize: an enema bag.
A little puzzled, I took my shorts off and entered the shower stall where Grandma was shampooing her hair. I washed my own hair, then took the bar of soap and started on Grandma's back. I slowly massaged her back, then worked down to her ass, cupping her cheeks before running my finger down her crack and tickling her rosebud.
She chuckled deeply. "I'm already clean there--inside and out." She gave me a hot look over her shoulder, and I figured out what the enema bag had been for. She handed me a bottle from the shampoo rack, which I quickly realized was lubricant, and spread her legs as she braced herself against the wall. I moved behind her, placing myself in front of the shower spray so that the lube wouldn't wash away, and squeezed out a generous dollop into the palm of my hand and ran it up and down her crack, then gently pressed a finger into her anus, moving it gently in and out until she loosened up, then adding another finger and repeating. After she could take three fingers--moaning softly as I pumped them in and out--I decided she was ready, and lubed up my cock, then placing the head at her rosebud, slowly but firmly popped it in.
She gasped and started breathing deeply. I started stroking in, a fraction of an inch at a time; it was so much better than my hand the previous morning. If fucking my grandma was forbidden, this was another taboo order of magnitude entirely. Pretty soon, we were grunting in unison as my cock sawed in and out of her ass, slowly but steadily. Even with all the times I'd come in the previous day and a half, I could feel my come rising fast, so I slowed down and gave Grandma a reach-around to her clit. She sighed and moaned, "Oh, Johnny, keep fucking me up the ass like that, I want your big hard cock up my ass every day, buttfuck your Granny, oh baby..." Even at a slower pace, it wasn't long before our moans and grunts reverberated off the shower stall walls as she shuddered and I shot my wad deep into her rectum.
Well, school is going fine, and I get along just fine with my classmates. I've been to a few parties and had lunch with a few women, but I don't feel in any hurry to take things any further. Every now and then, when someone finds out that I live off campus, they immediately suggest a kegger; I have to tell them that I live with my grandma and that she's home almost every night. They make a big show of sympathy and say, "Dude, what a drag."
If they only knew.