Bellybation 

The act of rubbing one's belly in a sensual manner with the intent of self pleasure.

Zack stop your bellybation obsession!

Bellybation by DDRIZZLE23 January 18, 2015

Mr. Bellybutton 

Mr, Bellybutton is someone that you will hate or be friends with. Mr. Bellybutton is overweight and walks around with his bellybutton hanging out.

Did you see Mr. Bellybutton's stomach?!?! IT WAS HUGE!!!

Mr. Bellybutton by ⒾⓐⓜⓈⓄⓊⓅ December 3, 2018

Bellybutton bargain

A bellybutton bargain is someone who is rather large/heavy/fat/overweight/or pleasantly plump.
It can also mean that someone has an obsession for bellybuttons

Person1:Jude man look, it’s a bargain.

Person2: holy shit man you’re right, that is a fucking bellybutton Bargain.

Bellybutton bargain by Press watches March 4, 2023

bellybutton gook 

the dirt, debris, and dead skin cells that collect in the pool of an innie bellybutton.

bellybutton gook is yummy

bellybutton gook by sweet-ass April 29, 2006

bellybuttoning 

It's when I stick my finger in your bellybutton!

Yelling "bellybuttoning" while I put my finger in your belly button.

bellybuttoning by YOLO212121 February 2, 2014

bellybutton glow in the dark 

A Zarry Stylik tweet

you make my bellybutton glow in the dark

bellybutton glow in the dark by Harry's Canyon Moon February 28, 2021

Glass Bellybutton

So one can see were they go when there head, is so far up there ass.

I know a few people who could use a glass bellybutton.

Glass Bellybutton by Roldgold_494 October 9, 2008