Conor McGregor Goes 'Stark Bullock Naked' ... On a Horse (PHOTOS)

Conor McGregor is going balls out to promote the Pegasus World Cup horse race ... well, ALMOST balls out.

The UFC superstar stripped down to his nude-colored skivvies for a new spot to promote the January 28th race for a comedic bit with Jon Lovitz.

Just glad Conor didn't hurt himself ... he's got a big boxing match to prep for.