At the beginning of the round a bet amount, say $1.00 per Arnie, is determined. Should a player manage to make par or better on a hole without finding the fairway, he/she wins an Arnie. At the end of the round, Arnies are counted up and bets settled.
This game can be fun because it helps players concentrate a bit more when they miss a fairway. A good way of taking a negative and turning it positive.