Conor McGregor Ballin' Out on Friday ... Rolexes For My Sisters! (PHOTO)

How will you spend your Friday? Conor McGregor spent his in a jewelry store in Ireland buying ROLEXES for his sisters!

The UFC superstar hit up Weir & Sons in Dublin along with his sisters, Aoife and Erin ... and showered them in fancy timepieces ... just because he felt like it.