A phrase created by Subject C (cannot put personal names on Urban Dictionary) that has no particular meaning, but its purpose is to be said out of random to release any exhaust of emotions.
Ms. A: Everyone did horrible on their essay!
Kid 1: Oh really?
Kid 2: Bartle Doo!
Ms. A: What does that mean? Do you like to annoy me?
Kid 2: It doesnt really have a meaning....
Ms. A: So can anyone tell me the meaning of line 5 in Act 3 scene 4?
Kid 1: Bartle Doo!
Kid 2: Bartle Doo.
Ms. A: Anyone else?
Entire Class: Bartle Doooooo!!