The act of whistling while taking a shit. Usually used to calm ones-self after eating too much Chipotle. Can also be used to freak out man in stall next to you.
Man: *whistle* whistle* oh god damn it Chipotle! *SHART!* *whistle*.... ahhh much better!
Usher: God Damn! that's the best Whistle Shitting I've ever heard! Yo wanna contract?!