Clean someone else's manatee
Basically it means stop wasting my fucking time and go bug someone else. An example would be:
Person 1: Hey, hey, hey, hey, what do you think clouds taste like? Like, like cotten candy?
Person 2: God bro don't you got to clean someone else's manatee?
Person 2: God bro don't you got to clean someone else's manatee?