Mary's hand fell now, but in a caress. She gasped aloud as the heat of his ass against her palm forced a throbbing flex of her cunt. Steve held his body rigid over the bed, waiting for a hand to descend with a loud smack upon his naked ass.

But Mary moved her palm across his bare ass, feeling the flesh and becoming intensely excited. She dropped to her knees behind him, peering between his thighs at his dangling balls. She drew her hand down his ass lightly and prodded a fingertip against his balls. Steve moaned, and his naked ass shivered. But he remained perfectly still.

"Oh, God!" Mary mewled. "I can't."

She brought her hand back up to the cheek of his ass and rubbed. Mary's other hand moved to her tits, digging fingers into the tit mounds through the bikini halter. She felt her son's ass shake underneath her hand. Impulsively, she leaned down and kissed his ass cheek, finding her lips burned with desire.

A glassy expression came into her eyes, and a slight flush of excitement suffused her lovely face. She could not rise from her knees or release her eyes from his cock. She knew it would be best to at least turn her face, but she couldn't do that either.

Steve's cock was swelling before her eyes, becoming hard. Her hand was still gripping her tit, and he saw it. What fear Steve had of being spanked was gone, replaced by a burning interest.

Mary could not stop her hand from exploring.

It moved as though separate from her body and her mind. She trailed a fingertip along his thigh, over his balls, and up the rigid shaft of her son's cock. She brushed the finger lightly over his swollen cockhead. Soft moans rose from her, but she wasn't aware of them. Her fingertip burned as if it had been shoved into boiling water. And she couldn't pull it away.