one day i was diving in sharm el sheik egypt, at the end of the dive (a from shore dive) was close to the shore, nearly 1-2M from surface, so i was so close to swimmers, anyway i wanted to go a little deep to avoid them, so i had to empty my jacket "BCD" in order to dive, when the air goes out from the back valve, i found that some snorkeles saw me and thought its a fart, was very funny the way they looked, hehehe