Hotlips

Major Margaret "Hot Lips" Houlihan was a popular character on T.V's M*A*S*H

(Describing Frank and Hotlips in a letter to his wife)
Col. Potter: She's the head nurse. He's the head twerp.

Houlihan's

The last few mmillimetres of a joint where taking a puff will result in 'Hotlips'

....also known as butt-slut

"Hey, do you want this?"
"No way! I ain't taken none of yo' HOULIHAN'S!"

butt-slut

a person who is willing to take the last few puffs of the joint close to the 'butt'

"you want the last toke on this joint man?"
"yeah, you know i'm a butt-slut"