"Uh, uh, uh-uh-uh," Mom panted, her yelps coming so close together they were almost one word. "Holy fuck, Mark--god!"

I slowed down.

Mom sighed.

I sped up.

Mom gasped.

I straightened my forefinger and eased it against Mom's lubed-up asshole alongside my middle digit.

"Oh, no, baby, no," Mom groaned, but she never used the word stop.

I ringed her pucker with the tip of my finger, gathering the extra lube that made her skin shine. I eased the tip between my middle finger and her sphincter and found that there was no room to get inside her anus. I prodded my mother's asshole, pushing the rubbery skin inward and...