A word used to describe the relationship between two males, whom have found they had intercourse with the same male, mutually known by both (much like eskimo brothers).
Chad: Dood you will never guess who I banged last night.
Brad: Who?
Chad: I totally fucked the shit out of Chet!
Brad: Ohhh man no way! I totally fucked Chet in the ass too!
Chad: No way! When?
Brad: Remember when Chuck had that awesome Christmas party last year? Totally pounded Chet in Chucks champagne room then, he was so loose!
Chad: No way! That makes us unicorn brothers!
Brad: Fuck Yeah Unicorn brothers for life!
*Brad and Chad then preform a high five
Chad: Dood, Chet is such a butt slut...