Wet Philly

Taking your index finger, sticking it up your ass, and then putting it in another person's ear.

It is similar to a wet willy, except with shit on your finger instead of saliva, which shares a similar color with the steak on Philly cheesesteaks (hence its name).

John- "I totally just gave Janet a wet philly!"
Billy- "No fucking way dude let's go!!! #ftb"