"Fuck me, Jack. Fuck my ass. Your cock feels so good inside my ass. Fuck me in the ass, Jack!" I start pumping in and out of my mother's tight asshole, going faster and faster until I'm slamming into her.
"Ohhh yeah, Jack, slam your balls up against my pussy like that. That feels so fucking good!" Mom moans, continuing to eat Lisa's pussy.
"I can't believe you're fucking Mom in the ass while she's eating me, Jack! How does it feel?" Lisa is smiling at me, pinching and pulling her own nipples as Mom eats her out.
"It feels incredible. Her ass is tighter than your pussy, Sis, and I didn't think anything would be tighter than that!" I'm watching my sister squirm around, pulling hard on her nipples, as I hear Mom's tongue slurping up her pussy juices.
"Can we all come together, do you think? I only ask because I'm getting ready to shoot my load up Mom's ass." Mom is eating Lisa furiously, rubbing her thumb across Lisa's clit and rubbing her own clit with her other hand, while I slam my hard cock in and out of her ass.
"I'm cumming, Jack. Don't stop. I'm going to cum so hard!" Mom is rubbing her clit and slamming her ass back against my cock, while I'm hammering her as hard as I can.
"Me too, Mom! That's perfect. Just what you're doing there! Oh god, I'm cumming!" Lisa yells just as I shoot my second load of cum inside my mother, this one deep inside her ass. Lisa is holding Mom's face tightly against her pussy, while I'm jerking violently in her asshole. I feel Mom shudder then relax as her own orgasm rolls over her. We sort of fall in a heap on the bed, Mom's face in Lisa's crotch and my cock slipping from Mom's ass with a popping sound.
"Let's rest for a while," Mom says, panting, "then I want to watch you fuck your sister, Jack. We only have a month until your father gets home and I want to make the most of it."
We do make the most of the next month. We fuck, suck and daisy chain in every conceivable position. I fuck Mom or Lisa while they eat each other. One of them sucks me while I eat the other one. We all sleep in Mom's king-sized bed, with me usually sandwiched between their sexy naked bodies. Mom and Lisa both have voracious sexual appetites and I quite frequently wake up with one of them sucking my cock. I fuck Mom before she goes to work, then Lisa and I fuck all day and are waiting to ravage Mom's body when she gets home. Lisa introduces Mom to the harness, and Mom teaches us a few things, too. Mom says it's the best sex she's ever had and suddenly we aren't looking forward to dad getting home.
Mom makes Lisa and I promise not to mention any of this to dad or do anything to make him suspicious. We agree, but we are all pretty frustrated within a week after he gets home. In September, Lisa and I move up to Los Angeles to attend college. Mom convinces Dad that it's better for us to live in an apartment off campus than to be in the co-ed dorms. She rents us a two bedroom furnished apartment close to the campus. For appearance purposes, we maintain separate bedrooms but Lisa and I sleep together every night.
Mom visits every other weekend and we pick up right where we left off. Mom complains that we've ruined her for anything but three-way sex and she always has something new she wants to try. She says dad has always been a wham-bam thank-you man, who satisfies himself, then rolls over and goes to sleep. She confides that the vibrator isn't just for when he's at sea. She tells us her sexual appetite has been dormant for a long time, but now that we've awakened it, she has proven to be as adventurous a sexual experimenter as Lisa. Between the two of them we have experimented with everything from homemade porn videos to mild forms of bondage and even butt plugs. There is nothing they won't try, which is all right with me. I'm just living out my fantasies.