Earlier quoted context omitted.
"pee" and "poop" are like the base terms for those two things. With "piss" and "shit" being the crude terms, and "poo" or "wee" being the more childish terms. This is the most stupid conversation I've ever had on this website.
Frankly it's more infantile that Americans insist on talking about "restrooms" when it's clear you're not going there to have a lie-down.
Restroom is one of those writing-only words, in my experience.