Peter Abraham lists the ten people to avoid at the ballpark:
4. People who keep getting up. Over nine innings, you should get up once, twice if you’re female. Go to the bathroom, get something to eat then sit back down and don’t get up again until the game is over. Stop making people in your row get up.
5. People waving signs trying to get on ESPN or Fox. This isn’t a game show. Sit down.
(…)
8. People trying to start The Wave. The Wave is a plague on sports. It’s 50,000 people saying, “Look at us, we’re all mindless and we don’t care about the game.” Thankfully Yankee Stadium is largely Waveless.
9. Trampy girls at batting practice. This always brings a smile. No matter what stadium you’re in, you see scantily clad women in stripper heels posing near the dugout trying to catch the attention of the players. This strategy may work in the minors. But do you really think Jeter is going to look up and say, “Hey, purple halter, Room 812 at the Westin tonight.”
Heh.

