The UFC star, who suffered defeat in his Las Vegas superfight against Floyd Mayweather back in August, was in Scotland for 'An Evening with Conor McGregor' event.
'The Notorious' started as he intended to go on, immediately grabbing a microphone upon taking to the stage to bellow: "What’s up Glasgow Celtic?! The only football club around here worth talking about."
With the mood set, McGregor then proceeded to chant: "Glasgow is green and white!"
While many of those in attendance greeted the Irishman with open arms, not everybody was enamoured with his antics.
Later in the evening, McGregor started to stir the pot again, roaring to the crowd: "Where’s Rangers at? I thought so! I thought so!"
The 29-year-old soon found out where they were as he was covered by a drink thrown from the crowd.
Rangers fan throws a drink over Conor McGregor for singing a Celtic tribute song in Glasgow. pic.twitter.com/wLgzyo0CiU— UFC Related (@UFCrelated) October 2, 2017
McGregor has acknowledged being a football fan, but has caused confusion as to where his allegiances lie.
While there is no doubting on which side of the Old Firm divide he sits, his preference in the Premier League is a little less certain.
In a column for the Irish Independent back in 2015 he wrote: "I was big into football as a kid, but more as a player than a watcher. I suppose if you pushed me I would say Manchester United, but that’s only because it gets passed down from generation to generation.
"I think just about everyone in Ireland is either a Liverpool or United fan. But some people go a little weird, referring to the team they support as 'we'. To me that’s a little crazy.
“I admire their athleticism and their dedication. [Cristiano] Ronaldo is a phenomenal athlete. His speed, his takeoff from a standing start and his ability to operate at high speeds are impressive."
McGregor did, however, appear to contradict himself earlier in 2017 when he was caught on video telling fans during a trip to Aintree: "I’m red...f**k Everton" — indicating he's become a Liverpool supporter.