Around the Horn: A double play that goes around from third base to second base to first base.
Bag: a base
Bang-bang play: a play where the runner hit's the bag a moment before the ball, or vice versa
Bronx cheer: Wen the crowd boo's.
Can of Corn: An easy catch by the fielder.
Cheese: a good fastball
Circus catch: and outstanding catch by a fielder.
Dinger: A home run
Dish: home plate
Closer: A team's relief pitcher that finishes, or "closes" the game.
Hill: pitcher's mound
Hot corner: third base
in the hole: the batter after the on-deck hitter.
Mendoza line: a batting average around .200
pickle: when a batter is trapped between two bases as the two basemen throw the ball back and forth.
punchout: a strike out.
rhubarb: a fight or scuffle.
tool's of ignorance: a catcher's equipment.