Boasting or having an inordinate amount of hubris for one's self, even when it's perfectly obvious to everyone else that it is absurd and undeserved. Often associated with severe denial, ala Charlie Sheen.
"John is walking around gloating like he singlehandedly won the big game for us, when he spent 58 minutes on the bench."
"Yeah, he's totally Sheen Winning."
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