bathtub gin 

liquor made in one's own home (because during prohibition they filled the favored bottles at the bathtub instead of the kitchen sink, can be applied to more than gin)

I wouldn't be caught dead drinking that bathtub gin.

bathtub gin by The Return of Light Joker February 16, 2009

bathtubbin' 

Hanging out with your friends in a bathtub.

We were going bathtubbin' last night.

bathtubbin' by Haruka Hoshino December 4, 2009

Bathtubbin' 

V. Getting with a friend on the swing and swinging your head back and putting your feet up, wrapping them around the chains and hanging. Usually includes laughing.

TBaww and Hacob laughed at the girl laying on the ground after she attempted to copy them while they were bathtubbin'

Bathtubbin' by Hacob SPeni February 8, 2007

Bathtubbing 

When you go down on a girl and she still full from the guy before

I just went down on this chick but she was bathtubbing

Fill her up like a bathtub

Bathtubbing by Onacid1990 June 16, 2018

bathtubbing 

The act of drinking someone else's used bath tub water. Especially after a gross encounter.

"Dude I just went bathtubbing in my neighbor's house! It tasted great!"

bathtubbing by BlackZoidberg July 4, 2017