i got locked in a toilet with a floor to ceiling door (so no gap at either end to call out or try to crawl under etc) when i was a child at swimming lessons... i have no idea how long it was for, probably not long at all since my parents were there and would have been waiting for me and wondering where i was, but i am a SEVERE claustrohobic now.... probably due to this but also i am sure my brothers putting beanbags on top of me then sitting on them also didnt help.