Cheeks jumpin

Certain movements initiate the process of buttcheeks bouncing up and down.

Hopping on one leg for example. Repeatedly hopping on one's tippy toes. Or having ones Cheeks crammed and the glutes jumping like they're doing jumping Jackson. Something as simple as tripping while walking can cause the Cheeks to jump. Can also be used to describe the current scene when encountering one or more thick buttcheeked individuals.

"My are Cheeks jumpin right now smh "
"Cheeks jumpin?"
"I see some Cheeks jumpin in this muf tonight cuh"