MLB Network's Dan Plesac Unloads F-Bombs Live On Air, Unaware Of Hot Mic!

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 ... "He was still the only guy that when he walked into the box I'm like, 'God damnit, I made it.' Swear to God. I was like, 'I made it.' Like f***ing Reggie!"

The talk continued for at least another minute or two ... with Plesac unloading another VERY audible f-bomb!!

Finally, the guys realized they were on the air ... and they all let out a huge chuckle over their not-so-G-rated conversations being broadcast to the world!!

Plesac ended up having fun with it all night, he joked about the gaffe throughout the show ... and even made reference to it in a tweet later while Tigers pitcher Spencer Turnbull was in the middle of his no-hit bid.

"The Tigers Spencer Turnbull has a 'NO NO' thru 8IP," Plesac wrote. "@tigers lead 4-0 going B9th in Seattle .... I’m not 'F’ing' kidding."

Hilarious.