EXCLUSIVE

There's nothing more beautiful than a bride on her wedding day ... but that might not be the case when the bride is punk legend Fat Mike.

The lead singer of NOFX and his now wife, Soma Snakeoil, eloped during a secret Vegas wedding on New Year's Eve ... TMZ has learned.

The unconventional couple decided to exchange vows as the opposite genders when they planned the wedding -- which we're told was only a week before the ceremony.

Sources close to the couple tell us Matt Skiba from Blink 182 and Alkaline Trio was Mike's best man and "bridesman." The guest list was only 8 people and the dress code was lots of black and even more leather.