The thread is simple -- what championship teams wore the WRONG jersey, sweater, uniform, etc. I don't want to limit this to just championship winning teams, so maybe the finalists of that league's championship round (ie-Super Bowl, World Series, NBA Finals, Stanley Cup Final, etc.).
Here are a few examples to get the ball rolling ...
Washington Capitals, 1998 Stanley Cup Finalist
Cleveland Cavaliers, 2016 NBA Champions
Edmonton Oilers, 2006 Stanley Cup Finalist