I've even heard someone in this forum mention they have unsnapped the bcd and unzipped in the middle of a dive and went pee.. Doesn't seem too common, though, heh. but some people prefer the warmth it brings :worried:
I've dived with an instructor who claimed to have removed a wet suit on a training dive on the bottom of course to relieve #2 due to having eaten something unsettling. Apparently a group of students divers happened to swim by above him shorly after the act and before he got the suit back on - smile and wave...
I for one am tired of the back zip and intend to buy a front zip the next wet suit I purchase. I often need help with the back zip when the suit gets old and the inner flap never lays flat.