Conor McGregor Dances And Downs Guinness For St. Paddy's Day Rager

It's the most wonderful time of the year for Conor McGregor ... and the UFC superstar is celebrating his St. Paddy's Day with some epic boozin' and dancin'!!

32-year-old McGregor and his fiancee, Dee Devlin, honored the patron saint of Ireland from the comfort of his own at-home bar ... which is complete with Guinness and Heineken ON DRAFT!!!

Conor kicked things off with an Irish jig to Dropkick Murphys' "I'm Shipping Up To Boston" blaring in the background ... all while holding a pint in his hands!!

Things then made it to the bar, where McGregor propped his feet up and continued to down some liquid goodness ... we're sure he had some of his signature Proper 12 whiskey in the mix.

"Tis’ the month of the Irish and I’m having my feet up and celebrating every last damn second of it," Conor said Wednesday. "For we will rise and then rise again! As you will never. And I mean NEVER beat Ireland!"

"Up the Irish ☘️ Happy Paddy’s Day everyone, enjoy it all month with me!"

Enjoy the big day, Conor ... and remember to mix some water in there at some point.