I was done biting my lip. I wanted to let it out. The pressure building inside me was too much to hold back.

"Sure," Mom said, cranking the volume. The heavy bass vibrated through the seats, perfectly masking the frantic rhythm of my body grinding against his.

I let out a low, shaky moan, finally free. It felt so wrong—and so good—to be completely filled by him while my mother drove us.

As I bounced on his lap, he slapped my ass—hard. The sharp sting pushed me closer to the edge. I sank back down, taking all of him, grinding my hips with desperate need.

"What was that noise?" Mom...