The Trampoline 

Where you extend the foreskin of your nutsack to form a "trampoline" and you bounce your penis off it creating the effect of a trampoline.

Guy 1: Hey dude, check this out
Guy 2: Ohhhh man... wtf
Guy 3: THE TRAMPOLINE!

The Trampoline by Weak Saucer November 29, 2007

Little Man on the Trampoline

The act of grabbing the sides of your scrotum and pulling it taught whilst you bounce your penis up and down on it.

My girl likes it when I show her the "little man on the trampoline"

Little Man on the Trampoline by Steve-o and Tim December 15, 2008

The wet trampoline 

When a pragenant woman expells crap and smears in in a curculatory motion on her stomach. The man then masturbates in side the "shit curcle" and slaps the pragenant belly.

Cindy even though you are preagnant I still find you attractive. Let me give you the wet trampoline

The wet trampoline by tramp dog May 17, 2008

The Bad Kind of Trampolining 

This unused and long term is used for when a NSFW video / gif or a normal video / gif is cropped to where someone "trampolining" looks like the person or thing is getting railed by something or someone.

Ben: Look at this anime character trampoline .
Jerome: Hm, that looks wrong.
Avery: Oh what the fuck, that's The Bad Kind of Trampolining.

The Bad Kind of Trampolining by DumbassOofGuy April 7, 2021