I can only imagine what people think when they see me doing 70 down the highway with my reverse lights on...

Anyway, is this something I can fix myself? Is it quick and easy or will it take a while? I'm a complete noob when it comes to cars so I have no idea where to start.

 

Someone switched the wires on the reverse/5th gear switch. The switch is on the back/side of the transmission, and has 4 wires going to it. One side has the circuit completed when in 5th gear (for emissions purposes), and the other side has the circuit completed when in reverse. Switch it and your lights will stop coming on in 5th. The connections aren't polar either, so it can't be backwards; just on the wrong half of the switch.