ISYMFS 

The acronym for it's Still Yo Mother Fuckin' Set.

A term used bodybuilders and weightlifters alike indicating you have not completed a repetition for a particular workout.

Guy 1: My girl just called. I gotta be outta here.

Guy 2: You cannot leave just yet. ISYMFS

ISYMFS by jasonthecancer March 27, 2014

ISYMFS 

The acronym for I Suck Your Mother's Fingers Slowly.

Term used by MILF lovers and feet fetishists. Often tattooed on different body parts to inform cougars about your preferences.

Woman: Hey is that ISYMFS on Your arm?
Boy: Yes it is.
Woman: Let's go to my house and talk about it.

ISYMFS by MichealQA August 13, 2019

ISYMSCOTC 

I Saw Your Mom Smoking Crack On The Corner

The proper shorthand response to any non-WFR Beer Bike cheer.

Hanszen, Hanszen yah.

ISYMSCOTC!

ISYMSCOTC by MrErlo March 24, 2010