The scene has Brain being cross-examined by a lawyer. For reasons that aren't important here, but have everything to do with his plan to take over the world, Brain has to convince everyone that he's just a dumb mouse and the lawyer is trying to show that he's not really a mouse but a mad scientist.

Paraphrasing, possibly badly, from memory....

Lawyer: What if I told you the moon was made of green cheese? Would you have a problem with that?

Brain, (scoffing): Hardly. In fact it makes me a bit peckish.

Lawyer: And what if I told you that Albert Einstein was the lead singer for the Monkees?

Brain, (bristling): Well, I really wouldn't know.

Lawyer: Oh, I see, I see. Did you happen to know, Mr. Brain, that the Fermi-Dirac distribution is a soup kitchen over on 51st Street?

Brain, (exploding): The Fermi-Dirac distribution is the probability a particle with half-integer spin will be in a given energy state E. My God, man! Don't you know your quantum statistics?!

Lawyer: I rest my case, your Honor.

It probably has to be seen to be as funny as I remember it. But I'm LMAO right now recalling it. Oh well. Whew!

Now my next question is, why did they put a cartoon meant for us physics graduate students on at 10am?