The lewdness of the act made Martha shiver with lust. She had sometimes wondered what Frank and Claire did in bed and now she was finding out! People were so different when they were alone in a bedroom!

Claire was the mother of two teenage children, but at the moment she was behaving like a wanton hussy.

Martha had always thought that sucking a man's cock was the most perverted thing in the world. Watching her sister do it filled her with a combination of repulsion and lust.

"Christ!" Frank hissed. "What a mouth!" Claire pulled her lips off his cock and giggled. She looked up at him.

"You like it, huh?"

She fisted the saliva-coated shaft of his cock and pumped it few times. Then she got to her feet and they kissed. Frank's hand groped down her body and between her legs.

Martha could see his fingers working in Claire's cunt lips. Claire began to moan and pump her pussy back and forth against her husband's hand.

"Oh, God! I'm hot!" Claire groaned. "Put your finger inside!"

Frank chuckled. "Get on the bed!"

"You don't think there's any chance of the kids barging in, do you?" Claire asked.

"They're not even in the house," Frank said. "Anyway I thought we had an agreement about that."

"I guess you're right," Claire said as she climbed onto the bed.

The blonde remained on her knees with her ass facing Frank. He lowered his head now and kissed her bare ass cheeks. Then he splayed his hands over the big globes and nuzzled his face in the crack between them.

Claire purred her approval. She groaned when his hands slipped between her thighs to massage her pussy. A mewl of delight escaped her throat when he slipped a finger deep inside her cunt hole.