I gotta go use the mathroom - When someone says they're going to the mathroom, it's just a

When someone says they're going to the mathroom, it's just a fancy way of saying they're going to pee. No one knows why they bother.

I gotta go use the mathroom. I can't hold it anymore.

He said mathroom like it was a secret code.

Why can't you just say bathroom? You're making it sound hard.