Ass Flop
The top part of the ass that flops out of fat peoples pants when they get up from previously sitting down.
Dude your friend Zach has some serious ass flop going down.
Flop ass
Basically a synonym for douchebag. Can mean anyone that is either scurvy, a putz, stupid, lame, dorky, or a nerd.
That guy has rubber testicles hanging from his back bumper, what a flop ass!!
So you spent all last night Watching MadTV? You are a flop ass!
So you spent all last night Watching MadTV? You are a flop ass!
Flip flop ass drop
This is when you are riding public transit and you offer someone your seat, only to stand next to them and fart directly in their face.
The kind young man offered his seat on the bus to an elderly woman. Moments later, the look on her face made it clear that she had fallen victim to the flip flop ass drop.