Want really funny?
While on vacation there were tons of divers around (club med). One of the instructors was joking that our hand signals needed work. In the end of one of the evenings 6 or 7 of us cordinated a totally unplanned toss in the pool using hand singnals when he appeared for a beer that evening. When we told him how things we set him up he laughed and said ok ok I take it back.
Even further then that what is scary is at a place like that you can cordinate dinner, who needs what from the bar, and when everyone is going to meet later and nobody needs to say a word. Funny thing about it is, no body even bats an eye at you and they just go, oh there divers....