Is it normal to clench and unclench buttcheeks to a song beat?

I do it sometimes, alternating them like you would with hands on bongos. or kick and snare drum.
They're not well trained enough to manage 6/8 time though.

I can do it with one cheek. Two, and simultaneously. And yes they do seem to tighten up the buttcheeks.

I was doing it once as i got pulled over for speeding. .. was quite a party.

Good, now try flexing one buttcheek at a time.

Wiggily butt cheeks

Yes. Take that gluteus to the maximus. We were given butt muscles for a reason.

You are humping to the music. I do it too.

Well you must have nice tight buns