Pull an Oswego 

To choke during a Conference or National title game after having success all year.

Person 1: Do you realize that during the last 4 years Oswego hockey has made the national title game twice, and the final four two other times? They never were able to win a national championship.
Person 2: That's amazing, there's never been another team in hockey to pull an Oswego like that.

Pull an Oswego by Ronald Card December 6, 2013