smell button 

noun; The anus. The external opening of the rectum.

I poked her right in the smell button

smell button by Mikebeer February 18, 2007

belly button smell

Stick your finger in your belly button, give it a whiff... possibly the worst smell in the world!!

"When I stick my finger in my belly button smell is like poop"

belly button smell by Shithead. April 5, 2006

Smellybutton 

A particularly foul belly button odor typical of overweight and under showered people. It's a form of fromunda cheese.

"I stuck my finger in her smellybutton on accident and couldn't pick my nose for a month.

Smellybutton by MAXTAXIN March 20, 2017

smellybutton 

A bellybutton that smells. What the hell else would it mean?

Stuck my finger in my bellybutton this morning. That shit stinks. I've got a smellybutton, son.

smellybutton by A Nice Chunk of Bernice June 24, 2010