Originally of military origin; a double play on the word "cluster," both evoking multiple fuckups, as used in the term "cluster bomb," and evoking the oak leaf or star "cluster" insignia of the REMF who did the fucking.
Civilian: "That Big Dig is a complete clusterfuck from end to end. Over budget, over due, and now under water."
Incorrect, but sounds like fun: "The three of us got together and clusterfucked all night."
Player 2: Awesome! and I just sniped your ass while you were talking!
Player 1: Fuck! You backstabbing cockbite.
"Man, that Abby bitch is a total clusterfuck."
"God damn, Jason is such a clusterfuck... I'd love to shove my foot right up his ass."
Seb: Oh crap! You're getting cluster fucked!
Jelly Means: Fuck I died...