The term originated on Dec. 30 2004, when someone, under the guise of "having to leave to hang out with Don Masterson," really just went home to drop a deuce so large, God himself couldn't create a larger dump.

Usage includes but is not limited to: "Hanging out with Don," "Big Don is coming over," "Big Don has launched a full scale attack," or even "D(on)-Day."

Usage does NOT include referring to the actual deuce in question as Don Masterson, but actually the action is what is being referred to.
"Hold on, Big Don is coming over."

"Sorry I was late, I was hanging out with Don Masterson."

-Were you masturbating in there?
-No, Mt. Saint Masterson erupted.
by Swedish 1337balls. April 16, 2005
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