Julie placed her hands over her twin's tits, digging her fingers into them, feeling her tits through her robe. Her nipples strained in hardness. She began to whimper in voyeuristic pleasure and opened the tip of her robe. Ben swallowed as he saw his mother's lovely, firm tits Julie grinned at him wickedly and began to twist and pull at her own nipples. At the same time, she lifted her ass up off the chair, legs wide, and began to grind them wantonly. Dark hair showed along the edge of her soaked panty crotch, exciting not just her son, but her, too.

Becky squealed. "This is how we fuck, Mother!"

Julie's cunt sucked inward with a sweet sensation.

"Fuck?" she said, her voice whispery and thick.

"Oh, yes! This is the way I fuck Ben!"

"That isn't… you're not fucking," Julie breathed, squeezing her tit and trying to lift the fiery nipple to her tongue. "You're just rubbing at each other."

"We're fucking!" Becky insisted, wiggling her little ass back and forth.

Ben began to move, to arch his hips upward. His eyes were glassy with pleasure, yet he kept staring between his mother's thighs, at her uplifted crotch. Julie was twisting her ass about in tight short circles, licking her lips as she watched her daughter rubbing her cunt back and forth on Ben's cock. Perhaps they really didn't know his cock supposed to go inside her cunt to fuck. Maybe this rubbing at each other was all they knew, what they thought was fucking.

Ben was grunting now, his face turning pink. Becky was making more squeals, and her small ass moved faster. Although Julie couldn't see that well, she was sure her daughter was rubbing the hotness of her cunt lips along the shift of her brother's cock now. They were both getting ready to come – that was obvious.

Ben staffed swinging his hips up and down, and Becky banged her pussy against his cock. Soft, moist sounds came to Julie, inflaming her senses. Their movements were those of fucking, of a cock sliding in and out of a cunt, yet Ben's prick was not inside his sister's pussy.