"Yayfome" was first used by the Brits. It's earliest occurence is 1743, where an Earl shouted "DUDE! You just YAYFOME'D that n00b bitch!" Yayfome in latin literally means "Pwner of bitch ass n00bs". See The Great Yay
Dude. Did you see Yayfome pwn those n00bs the other day? He pulverized them! I wish he would have my children.