Rattle your mudflaps

1.To go take a huge shit.
2.To fart powerfully
3. A threat to violate your booty cheeks

1. Sorry, fellas, I gotta rattle my mudflaps somethin’ fierce. It’s gonna stank.
2. I heard that from across the house! Did you just rattle your mudflaps?

3. Now listen here, I’ll rattle your mudflaps like you’ve never had it before just to show you who’s boss.