Check this out. State championship. 50 seconds left. QB runs it in for the TD. Gets flagged for excessive celbration. The 15 yard penalty takes the kicker out of his extra point range (I guess he doesn't have a strong leg)so the coach is forced to go for two (the win rather than tie) which they don't get and lose the game.
Judge for yourself:
http://www.tricities.com/tristate/tri/sports/football/jiburtongame.html