I got a lift from a tourist from Boston when I was hitchhiking from Falkland to Auchtermuchty in Scotland
He had an A4 sheet of paper that his wife had taped to the front of the glove box that said "LEFT YA FUCKIN BOZO" to make sure he stayed on the right wrong side of the road
My wife learnt to drive here in the UK, she has a song she sings when she's anywhere with opposite sides for traffic. Goes something like: Right hand side of the road, right hand side of the road, dear god right hand side of the road....shit fuck, right hand side of the road!
If you actually are curious, they come in packs of 500 and we call that a reem of paper. They also come in boxes of 10 reems, and sometimes you can find a half a reem at the local shop but it's probably the same price as a reem.