What's fappaning

A mildly mocking question indicating you believe someone is masturbating.

Hey bro, what's fappaning in the toilet? Hahaha!

What's fappaning by I, Wreckerrr November 4, 2016

whats fappening 

to ask what is going on in one's sexual life, similar to asking whats happening.

guy 1: hey man whats fappening?
guy 2: eh very little, been on a dry streak lately.

whats fappening by w.e.e.b. July 28, 2011