With this being the first class, the students probably had some kind of expectation that their teacher would be on time. But no, the only thing at the front of the classroom was the teacher's desk and, next to it, a water cooler with a small WB logo on the plastic water jug.
Then the jug started to shake while
music filled the room. After a few seconds, the jug was thrown from the water cooler as a black and white puppy-looking thing stood up with his feet still in the water cooler's reservoir.
Any of this might have made more (or even any) sense if class were in the Danger Shop. It wasn't. As it was, the students would just have to convince themselves they weren't crazy as the teacher started to sing.
(And give him a break for starting with a variant on his own theme song. He was just getting warmed up!)
( He sings. AND SO WILL YOU. )