at 'em ball

• at'em ball
• at-'em ball

Because such a ball is hit straight at 'em (at them).

at 'em ball (plural at 'em balls)

1. (baseball, slang) A hard-hit batted ball hit straight at a fielder in the air for an out.
   • 1996, Mike Whiteford, How to Talk Baseball‎, →ISBN, page 76:

     If opposing hitters consistently hit balls at -Fielders, the fortunate pitcher is said, to be possessed of an "at 'em ball."

• meatball, metaball