We don't tell the campers until the last day of camp - and even then, only if they actually remember to ask. The ones that return to camp and know your real name think it is so cool that they know so they generally don't tell.
I did have an older sister send the younger one a list of camp names and real names one summer - would have been amusing if the girl hadn't insisted on telling the whole camp!
I find it hard to switch out of camp name mode when you leave camp. Some of my friends I've been friends with so long that it's not so bad - but those that you meet at camp - that's a hard thing. Shopping is much more fun when you are yelling "Crash!" across the store... Or you don't know the real name of that staff member. That happens too!
