another word for "duh" or "thought chu knew!". Basically a word made up by some leadership students at Capuchino High School. Became really known around campus through posters and also became part of a cheer for Varsity Volleyball players.
Guy: "Hey who won the bball game last night?"
Girl: "Uh Mills, whatchuthank?!?"
"Its the bay out here! Whatchuthank this is!?"
Girl goes up for a block against Hillsdale High. Team comes together and says, "Oooohhh hands in the air, blocking position WHAT-CHU-THANK!?"