1. The guy who thinks league bowling is his job and can never allow himself (or others) to have fun at it.
2. Power drinkers and wards of modern chemistry who can't enjoy any activity in their lives unless they're too wasted to remember any of it.
3. Folks who won't bowl when it's their turn. Includes the frequent bar flyers, the guy trying to hit on someone's girlfriend, dude-on-the-phone, the guy whose buddies come down to chat and always seem to start a conversation right when it's his time to get up there, etc.
4. Equipment snobs -- i.e., the guy who brings one ball to the lanes, which is fine for him, but if he sees someone with more than two balls goes into a b*tchfest about how he never needs more than one ball and how that ain't how they used to do it in the good ol' days and you're not half the bowler he is because you can't get it done with one rock, etc.
5. Folks who don't understand whatever the local lane courtesy rule is -- where I live, it's one-lane courtesy. But invariably we'll get the guy who, without any prior warning (usually sometime around the sixth or seventh frame of game 2) decides he needs two, three or four lanes courtesy, and expects you to have read his mind and know this. It usually manifests itself when you step up as always, and then suddenly hear someone slam a ball down into the rack two pairs of lanes away, and when you look over to investigate the sound, there's a guy glaring back at you. I just smile and wave. Goes back to No. 1, above.
Jess