Hilarious scene on the MLB Network on Tuesday night ... star analyst Dan Plesac didn't realize his mic was hot, and unloaded several f-bombs live on air!!!
The former Milwaukee Brewers pitcher -- and 3-time MLB All-Star -- was just beginning his shift on "MLB Tonight" when he thought he had some time before cameras began rolling.
Plesac was talking about Reggie Jackson, when the host of the show, Greg Amsinger, told him, "We're not on the air."
So, Dan then began to speak freely .