"Oh, Son, you're very good at that," Sharon purred.

"But you like it, don't you, baby? It's all right if you do, Mark. You don't have to be embarrassed. It's perfectly natural. You like massaging my big tits don't you?"

Mark obviously couldn't speak. His cock was obviously as hard as stone now, and Sharon could hardly believe how stiffly it throbbed and jerked under the fabric.

"Mark," she said innocently, "why do you have such a big hard-on? Is this really turning you on so much?"

Mark gasped, his face reddening brightly. Sharon lifted her hand and swiftly undid the knot holding the towel around his waist, letting it drop to the floor. Then it was her turn to gasp as she stared in wonder at her son's enormous prick.

"Oh, Mark! Mark, it's so big!"

His incredibly long, incredibly fat fuck-pole rose straight out of his big balls and cock-fur, throbbing and jerking stiffly in front of him. His cock-knob was big, puffed up to an incredible size by a skin-stretching load of blood. Sharon gasped as she watched his milky cockjuice oozing out of his piss-hole, coating his crimson cock-head with a sticky sheen of cum.

"I… I'm sorry, Mom," Mark sputtered. "I guess I just couldn't help it."

"I had no idea!" Sharon exclaimed. "Rubbing my tits did turn you on, didn't it, honey? Why, I think this is the biggest, stiffest cock I've ever seen in my life!"

Mark continued to look embarrassed until he realized that his mother was now stroking his hard-on, obviously enjoying herself as she slid her fingers lasciviously up and down his prick. His giant cock responded by squirting out more cock-juice onto her palms.

"Oh, my poor, poor baby," Sharon purred. "You're never going to be able to get to sleep with a hard-on like this. Would you like Mom to give you some relief, honey?"