One who possesses the ability to clog someone's toilet to the point of OVERFLOW (not merely backup or slow flush) causing shittywater to cover the entire tile floor and parts of the adjacent hallway carpeting. This is not intentional, and happens despite multiple courtesy flushes throughout the act leading to the final shitmastering flush.
Dave: (Running out of the bathroom) Where's your mop bro?
Me: What? Why?
Dave: Your toilet's overflowing man. Shit is literally EVERYWHERE!
Me: You're the fucking shitmaster dude... mad props. Now go clean it up.
A compound word using schadt and master in place of the more common compund word, 'shitmaster' while 'schadt' can be used in place of shit in any situation to sound posh, it is best paired with master.
1. Like a hipster, but smellier...
2. Someone who takes as much pride in shitting themselves publicly as most hipsters do of their unique and ironicmusic collections.
3. See also: douchebag