During a segment on the Hannity program on Fox News Monday night, Democrat panelist and host of The Five Bob Beckel dropped the F-bomb on live, and then, refused to apologize, though he eventually did on Twitter.

On Monday night's episode of Hannity, Beckel began an argument with panelist and tea party activist Jennifer Stefano of Americans for Prosperity, dropping the f-bomb without knowing they were back on air.

If you say that Head Start is a failure you don't know what the f--k you're talking about, Beckel said.

WHOA! Bleep! said host Sean Hannity.

Failure, said Stefano.

I just can't stand right wingers with their mouths running all the time. I don't apologize.

Yes, you do, said Hannity. You just cursed on air.

No, I don't. I'm not going to apologize, Beckel said.

Up his realization that they were on the air, Beckel said, We were not on the air.

Yeah, we really were, said Hannity. All right, I apologize for you.

Later on during the segment, Beckel decided to apologize, but halfheartedly.

I'm sorry about using that foul word, yes. But the intent about it is still there, Beckel said. You should run your show a little better instead of having me get caught like that.

The fight continued on when Hannity felt accused and Stefano called Beckel a typical liberal with no personal responsibility.

Bob Beckel eventually decided to formally apologize for his f-bomb gaffe on live television via Twitter.

I apologize to anyone who heard me on Hannity. I honestly thought we were off air. I just may not be cut out for the tv business. Peace, he wrote.

However, this is not the first time Beckel was foul-mouthed on television; In September 2011, Beckel said s-t during a report about Herman Cain and used the word again later that month talking about tax cuts. Similarly, he dropped the f-bomb in July about terrorism.

Here are some videos of his best potty mouth behavior incidents of all time, including his April 2012 gaffe.

April 2012

September 2011

September 2011, Part 2

July 2011