UFC Fight Night 59: Conor McGregor labels Dennis Siver a Nazi, then (sort of) apologizes

Ultimate Fighting Championship (UFC) featherweight Conor McGregor is probably still getting used to this whole "superstar" thing.

Or perhaps he just doesn't give a f--k.

The UFC Fight Night 59 headliner, who will be seen closing the FOX Sports 1 broadcast opposite Dennis Siver on Jan. 18 in Boston, Massachusetts, called his upcoming opponent a "Nazi," perhaps overlooking the fact that Siver was born in Russia.

Hoelzer Reich would be proud.

The tweet was quickly deleted and followed with a ham-handed apology (courtesy of Bloody Elbow).

McGregor is no stranger to Twitter boo-boos. Last year he tweeted his version of doomsday prepping, which included plans to have a three-way with UFC women's bantamweight champion Ronda Rousey and top division contender Miesha Tate (more on that here).

The promotion has been cracking down on mixed martial arts (MMA) fighters who spout off on Twitter. Then again, it also depends on the popularity of the fighter. Considering McGregor can shut down an entire country, he's likely to keep on keepin' on.