In my high school, the answer would be “because the toilets by the lunch room don’t have any toilet paper, or stall doors”.

Yes I’m American, why do you ask?

Who put toilets in the Gladiator room?

Because I’m not wasting my precious free time in a bathroom.

My answer was always, “I didn’t have to go then.”

My high school toilet stalls had no doors on them (can’t have them boy’s touchin’ themselves in Indiana! Jesus will find out!) so I either went during class or I held it in until I got home. That wasn’t fun.