The Lights are on but...

Nick (chap in IT) sent us all a logic problem on email the other day-

Inside a windowless room, there are 3 electric lights. Each light bulb is turned on by its own switch and the 3 switches are located out of sight of the room, in the corridor.
The only way of telling which switch operates which bulb is to go into the room.
However, for the purpose of this puzzle you are only allowed to enter the room once, although you may operate all 3 switches.
How can you discover which switch turns on which bulb?

Did you get that? Good. Now I didn't know the answer, I'll freely admit. Susan did. The answer according to Susan...

"The right one"

I'm sorry, the right one? Unfortunately I couldn't get her to explain her wisdom, as she quickly distanced herself from her original answer. She then asked...

"Are there any switches upstairs?"

Even as I write this, I'm questioning whether I actually heard that question, but I did. I don't know where she was going with it. She seems to be getting better at spotting my reaction to things, and she must have figured out that she was wrong from my look of incredulity.