I gotta go use the mathroom - A dumb way of saying you're going to pee, but you say it lik

A dumb way of saying you're going to pee, but you say it like you're doing something important. It's ridiculous.

I gotta go use the mathroom. It's a big deal, okay?

He said mathroom like it was the most important thing.

Why can't you just say bathroom? It's so dumb.