Originally Posted by Tuna

Since both of you already know Janszoon's one, I'll give you guys one to work on while I try to figure out that one:

There is a room with a single light bulb inside. On the outside of the room, there are three switches. Each switch is labelled 'ON/OFF' so you can tell what state they're in. One of these switches is attached to the light bulb, but the other two are not.

You begin with the room sealed off and with you on the outside of the room. You are allowed to play with the switches however you want and put them in any configuration you want. You are also allowed to walk in to the room and look at the light bulb whenever you want to - BUT you can ONLY DO THIS ONCE. The goal, of course, is to figure out which switch is attached to/controlling the light bulb. So, what would you have to do to figure it out?