Yet another term for sex. Much like, shag, bang, fuck and copulate.
It is the action of two people smashing their pelvic floors together.

It does what it says on the tin!
Man 1: yo, did you hear what Darren and Jessica were doing last night?
Man 2: yeah bro, they were smashing pelvic floors.
by WinterICE001 May 13, 2021
Get the Smashing Pelvic Floors mug.