"Happy birthday, dear," purrs Stepmom Susan, her eyes locked onto her stepson's nervous gaze. She's got a secret gift planned, one that's sure to make this birthday unforgettable. She guides him to the edge of the bed, pushing him down gently. With a wicked smile, she spreads his legs, her hands tracing the insides of his thighs. His cock twitches, and she grins, knowing he's eager for what's to come. She leans in, her breath hot on his ass, and begins to lick, her tongue exploring every contour of his tight, untouched hole. He gags at first, the sensation overwhelming, but she's relentless, her tongue pushing deeper, her hands stroking his cock in time with her rhythm.