My parents used to leave me near the computers in shopping malls when I was little. Shopping bored me to death, but I liked to fiddle with all the computers on the display. Trying to bypass some locks, just for the fun of it (and sometimes even succeeding! :)) and typing JavaScript into IE's address bar to display some fun stuff was always my main occupation :D Plus I didn't have to go with parents around the whole shop and they knew where to expect me.

I also vaguely remember escaping some "internet cafe" kiosk at some hotel during one of the abroad school trips. The kiosk had "broken" sticker on it and seemed actually broken, but some functionality still worked and after escaping the kiosk UI I was able to actually fix it (as we actually wanted to use it) - don't remember what was it though :( Some technician was probably either grateful for a null job afterwards, or lost an order due to me ;)