Conor McGregor uncorked a shot to the head of an elderly man in an Irish bar in a dispute over whiskey -- Conor's whiskey -- and TMZ Sports got this video showing the violence.
The absurd attack went down at The Marble Arch Pub in Dublin on April 6. Conor walked in and lined up cups for bar patrons ... looking to buy a round of his Proper Twelve for everyone. The problems started when the guy opted out. Conor placed a cup in front of him not once, but twice .