Make friends with that dick!

You look over at Joe. Or more importantly, at his cock. A full twelve inches, throbbing just slightly, a drop of pre-cum welling up from the tip. You can't turn your eyes away from it. You manege to stammer out "Oh. Like... Suck you off or...?" On the couch behind you, Mona giggles and leans forward. She puts a hand on your shoulder, saying "Oh come on now, Son! Don't tell me that you forgot already?" You look at her with confusion. "Forgot what?" She gives you a big smile. "I promised that i would teach you how to ride a dick!" You are understandably shocked. "You are?"
She brings you up to your feet. "Of course! I'll have you know that my sorority voted my Reverse Cowgirl best in show two years running at our annual invitational." She leads you up to Joe and his armchair and spins you around to face her. "And I won't have any child of mine not be able to live up to that. Riding dick is a valuable skill and it's high time you learned it." It's clear to you now that the time for backing out of this is over. You're getting fucked in the ass and that's final. "Alright Mom. Show me how it's done." She does a little clap of excitement. "Oh, Milo, that is just fantastic!" She glances down at her husband, who has spit into his hand and is running it up and down his cock. He says "Don't worry son, you've got the best teacher you could ever have."

Mona starts off by pushing you back a little. "Sit back, Honey. And don't forget to relax." You start to spread your legs a bit, squatting a tad to get closer to Joe's meat. "Don't let Dad do all the work. Help guide him in there." You grab the base of his dick as you start to sink onto it. His tip is thicker than it looks. It starts to slowly spread the tight muscle of your anus as you sink further and further onto his fat cock. A surprisingly feminine moan escapes your mouth as you take more of the dick. Soon, you feel his bush of pubic hair press against your butt-cheeks as you bottom out. "Oh my god, Joey, look! He got it all on his first try!" You can feel the hot meat pulse inside of you. "Spread your legs real wide so I can see!" You lean back and press against Joe's hairy chest. "I don't know if can, Mom. I can't really feel my legs right now." Joe smiles and moves his arms under yours, grabbing under your knees. "Don't worry sport, I've got it." He then lifts up your legs and spreads them wide, supporting your weight. Mona gasps in delight. "OH, Joey it's just beautiful! Wait, wait! Hold that pose, don't move!" She sprints out of the room and returns with a cell-phone in hand. "We absolutely need to commemorate this moment!"