"Jeff stop, I know you want to say something supportive, but listen to your sister for a moment."
Carol came over and sat on the couch beside her brother. She clasped his hand between both of hers. "You love Mom, we both do, but have you looked in a mirror lately? You're no jock, but you're starting to fill out." She glanced appreciatively at his penis, standing half erect from his thatch of pubic hair. "And you proved at dinner your cock has certainly matured into a yummy looking fuckstick of adult proportions, I know I'd be happy to take it for a spin, and I bet Mom would too!" She pressed his hand between her breasts. "Sometimes? Actions speak louder than words. If you want to help Mom overcome her compulsion to masturbate, get over there and give her something more satisfying!"
Anne sat frozen staring at her children, barely able to process what she'd just heard. Her body was aching for release; she usually managed a quick orgasm after dinner while Jeff and Carol washed the dishes, and Jeff had gotten her so damned horny playing with her tits. She realized she was panting and had stretched her legs out--spread them really--as she arched her back, feeling sweat trickle off her tits. She hadn't quite aimed her dripping wet pussy at her son, but she knew if he didn't get over there soon and mount her she'd be crawling into his lap begging for sex.
"You see?" Carol asked "She wants you to fuck her. I want you to fuck her, and I think, from how rapidly your dick is growing, that you want to fuck her." She shifted Jeff's hand to her breast, squeezing it. "Just, either save something for me, or let me get off while watching the two of you, okay?" She reached out and tenderly stroked the underside of Jeff's shaft.
Anne whined as she watched Carol fondle Jeff's cock. 'No!' She thought, 'Mine!' as she scrambled to her feet. At the same moment Jeff lurched off the couch, stepping away from his sister.
"Carol I--oof!" Jeff fell heavily with his mother on top of him. She pressed her mouth over his, cutting off what he'd been about to say as she began passionately kissing him. She was grinding her breasts and crotch against him, humping him frantically. Jeff got his hands on his mother's perfect ass and pulled her up high enough for his engorged penis to slide into her as she resumed humping, now with her son's thick cock filling her pussy. They stopped kissing as she shifted kneel astride him leaning back so his cock rubbed her g-spot. She was moaning and muttering how good Jeff was making her feel.
"C-Carol! I want you to masturbate while we fuck." Jeff called out. He owed her that much at least for touching off this powder keg. He felt his mom's pussy clamp down as she threw her head back and screamed, her body clenched in orgasm. Jeff grabbed her arms and pulled her limp body forwards, rubbing her back and pressing her sweaty breasts against him as she panted and twitched.
Anne's first thought, once she was able to think again, was how happy she was Jim could hold an erection long enough for her to have multiple orgasms. He was still inside her as she began sliding herself up and down his manhood. His chest was oddly hairless as she dragged her tits against it the way they both liked, had he shaved it? The sound of another woman pleasuring herself snapped her back to reality and Anne remembered it wasn't Jim she was fucking, but their son Jeff. That knowledge, and his hands on her waist, pulling her loins tight against him in an undeniable demonstration of his desire for her touched off another series of orgasms that had her shuddering and crying out in pleasure.
Carol watched her mother fuck with the ferocity of a wild animal. She could hardly believe it when her panting and moaning got Carol's pulse racing, and the two shared simultaneous orgasms without even touching eachother. Anne caught Carol's eye and blew her a kiss as she held Jeff's face to her breasts before her eyes slitted with pleasure at her son's licking and suckling.
"Oh Jeff! Yes baby, suck harder! Oh honey, oh honey!" Anne shivered as another orgasm sent her out of her mind. When the happy hazy clouds cleared and she was able to think again she was laying on her back and Jeff had her knees pulled up as he slammed his cock into her over and over and over. She began chanting to urge him on. "yes yes yes..."
Jeff felt the tension building in his balls as his mom urged him to pound her faster. His lungs felt like they were on fire as he tried desperately to get enough air to keep going. He felt his orgasm begin and buried himself as deep in his mother's pussy as he could. She was screaming with joy, and bit him on the shoulder as his seed pulsed into her. Jeff heard Carol scream as she came and realized she'd been keeping pace with them. He let go of his mother's legs and she hooked her ankles behind his back, rocking gently.
"What?" he asked, lying exhausted on top of her.
"Shhh shhh." Anne stroked her lover, running her fingers through his damp hair and concentrating on her yoga training.
Jeff felt more tension building in his loins. He cock throbbed, whatever she was doing was getting him hard again faster than he'd ever been ready to wank again in bed. He heard Carol sobbing on the couch, wet smacking noises confirming she too was still going strong.
Jeff tried to help, but his mother rolled the two of them over and resumed humping him. Jeff tried to catch his breath as she rode his body. He was limp except for the raging hard-on she'd induced in him. She leaned lower, the tips of her breasts dragging on his chest. He managed to bring him hands up to cup and squeeze them, his fingers sliding on her sweat-sheened flesh. She stopped suddenly, her pelvis grinding against his and her pussy squeezing his boner. She released the pressure as she rose up, slammed down again and clenched hard as she rose. Jeff felt himself coming again, stream after stream of sticky semen spurting out as his mother milked his cock with her body.
At last they lay still together on the floor, sweat drying on their skin. Jeff stared in wonder at the gentle smile on his mother's sleeping face.
"Hey, you alive?" Carol whispered loudly "Can I stop now?"
"Yeah." Jeff called, not sure what she meant.
"Jesus, you two went at it so long my arms feel like lead, but damn if that wasn't the sexiest thing I've ever seen. Including the boys' swim meet warm-up exercises.
"Oh, um, next time you can stop or take breaks if you need to." Jeff whispered back.
"Next time you can fuck me and Mom can watch, okay?" Carol replied. "You want a blanket or something?"
Jeff pulled the blanket over them, his mom murmuring in her sleep and snuggling against him. Jeff squeezed her ass gently and held her as he drifted off to sleep.