Someone who is passed out. Most commonly used at parties where someone passes out on a couch or the floor. Used in conjunction with the word "slump" or "slumped."
Friend: "Your boy Paul took like two hits and a shot, and was just slumped out on the couch. Everyone would just tap him on the head and say bye to him on their way out of the party."
Me: "Damn bro, so he was just Slumped Dog Millionaire, huh?"
Fiend: "Haha yeah bro he was slumped the fuck out."