Rudy Giuliani can't seem to remember the most important lesson in showbiz: the camera is Watch The Desk Girl Onlinealways watching.

Prior to the third presidential debate, Giuliani engaged in a face-off on CNN with Clinton surrogate Mark Cuban. Halfway through the conversation, Giuliani grabbed reporter Erin Burnett's wrist, and left it there until he finished his comment.

SEE ALSO: All the ways Rudy Giuliani was wrong about Hillary Clinton and 9/11

It's not uncommon for people to touch other people while making a point, but it's not okay unless that touch was invited.

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Here's video of the incident.

Aaaand for the close-up.

Giuliani has been one of Trump's loudest surrogates in the past few weeks. He argued that the Access Hollywoodvideo was just locker room talk and said that he "believed Trump" and his denials of recent serial allegations of sexual assault.

BONUS: Donald Trump called Hillary Clinton a 'lit woman' and it lit the internet