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Conor McGregor Bros Down With Fan ... Sick Tattoo, My Man!!!

Conor McGregor found a fan in Italy this week who had tatted the UFC star's face on his arm -- and he absolutely bro'd down with the guy to celebrate!!!

The clip -- which McGregor filmed himself -- is awesome ... the fighter looked the ink over up-and-down and praised it relentlessly.

"This is probably the best version, the best version of me," McGregor said, adding, "My man! Thank you, brother!"

The artwork featured a bearded McGregor surrounded by money signs ... and Conor loved it so much, he then threw his arm around the dude and took a selfie video.

The guys cheered and smiled ... and it seems like it was a blast for all involved.

Of course, Conor is a huge fan of body ink ... he's got some of the most recognizable tats in the world -- but as far as we know, there are no portraits of himself on the bod yet.

Maybe the trip to Rome will inspire it?? Stay tuned ...