Fox News had an unfortunate moment with a hot mic on Wednesday as one of the network’s guests was given a four-letter greeting.

The moment came as Laura Ingraham introduced far-right commentator Charlie Kirk for a segment on corporate leaders becoming more friendly to President-elect Donald Trump.

“Joining me now is someone who knows a little bit about this: Charlie Kirk, Turning Point USA founder,” she said.

“Oh, shit,” an off-camera voice said.

Mediate reported that an “audio operator accidentally slid the wrong fader,” catching another guest in the s-bomb.

It’s not clear who said it or if they were reacting to Kirk.

Check out the live TV moment below:

A source at Fox News told Mediaite that the remark was the result of an accident involving another guest’s microphone.

“The audio operator accidentally slid the wrong fader which was allotted for a different guest,” said the source. “That guest in turn was adjusting his IFB at the time and said ‘oh s***’ which was accidentally transmitted on the air.”