Gussy on his way back to be a big kid again, means back to school. If you think it's easy as it's not his first time there, well, bad luck. His mind has a lot of scrambled thoughts from things he learned back then. He basically needs to unscramble them, by learning them again.
Maybe Gus knows the answer to a question the teacher did? look at the golden stars at his uniform, he surely is a good student there.
Maybe he needs to go potty... uh.. naah. maybe needs a change? possibly.
And alternative versions without overalls. They're part of the uniform, but wthout them is easier for the teacher spot when he needs a change. And an alt with him just in diapers. Well, maybe he's asking for his clothes again?