Aren't Nixons afraid of wires?
There are some technical answers that would work, but I don't know if you'd accept them. One such answer: Turn on a single light, go to the garage, see which light correlates to the switch, then remove a different light bulb, then go back to the switches, and turning off the first, while turning on another. Then take a glance at your power meter to see how much electricity is being used, then turn on the last one, and if the meter goes up, the last one controls the last light bulb that is plugged in, while if it stays the same, the last switch is the for the light you took out. I doubt that's the answer, though.