Uh..it would be accidentally walking into the men's washroom.

In my college, the womens washrooms are never next to the mens. Theyre separated on to different floors. So the first and third floors are for the ladies, whereas the second floor belongs to the men.

I guess I forgot what floor I was on and accidentally walked in without reading the signs. Took a few steps toward the nearest stall before I saw like 10 guys standing on the other side, in front of mirrors. They stared at me; I stared back at them and then quickly walked out.