Shut up and pitch?

[HaraKiriBlade]

Another day at work.

A man with a haggy grey letter t-shirt on came in. The shirt had 'Shut up and pitch!' on it.

What does it mean?

[mykwyner]

I think this may refer to American baseball. In a baseball game, nothing can occur until the pitcher has thrown (pitched) the ball. To me it means, "Stop talking and do something," or "It's time for action, not words."