This comes from Brad at This Is Getting Old. He says that:
"I got this T-shirt in June of 2008 after the Bucs played the Yankees. Some lady was selling them for $5 on the Clemente Bridge. It's a picture of Maz hitting the most famous home run in World Series history."
The Clemente Bridge is an underrated spot for unlicensed/generic gear. So is beneath the overpasses near Heinz and PNC, if you can maneuver around the homeless begging for change. Not all unlicensed merch comes from the Strip District and World of Values, people.
Notice that the shirt doesn't mention the Pirates beating the Yankees at all. Oh it mention's Bill Mazeroski beating the NYY, but only goes so far as to use the Pirate's nickname.
I usually have a problem with most unlicensed merchandise, as they're mostly tacky and cheap. No problems whatsoever with this one, though. It's simple, commemorates one of the most important plays in World Series history and does so with only a picture and few words. Props to Brad for spotting an unlicensed winner and going for it. 5 dollars well spent.