1) That ONE guy with a cowbell/airhorn/drum/any other loud and annoying contraption that continuously beats on it or plays it all 9 innings!!
2) Cheaply made blankets/hats/tshirts being hocked by credit card companies
3) Drunk college kids!
4) Someone who thinks its cool to wear a jersey OTHER than a baseball one just because its a sports game, ie NY Giants to a Yankee game.
5) That one hardcase usher that sees you with a tray of nachos, hot dogs, and pretzels for your family, yet STILL thinks he needs to see your ticket even though you've already gone past 10 other checkpoints to get inside the stadium.
6) The guys out front looking to buy your tickets from you, or give you an upgraded seat for a "really good deal"...
7) Collectible cups all over the stadium at game's end.
8) Scoreboard/Jumbotron playing clips from Bull Durham, Major League, and any other baseball movie ever made
9) ICE cooooooooold BEER! Getcha COLD beer HERE!! ( I hate that guy)
10) Some little kid thats so excited to be there in the 1st inning, but by the 5th inning he's used the bathroom 6 times, eaten 3 hot dogs, and is now fallen asleep on their parent's lap.