I just thought about this embarrassing story from first year, it happened in one of my very first lectures. I was dying for the toilet and not knowing the 'just walk out' lecture etiquette, I waited for the lecturer to stop talking momentarily and put my hand up and asked to go to the toilet. Why does nobody tell you these things?!?
Looking back it was so cringey, but fortunately nobody remembered it so I avoided being called "toilet kid" or some sort of alternate, but equally hilarious, nickname for the rest of my time at university.