Fair Weather Fan
Definition: "A fan of a sports team who only shows support when the team is doing well. They have no real loyalty to the team, but still manage to get better seats than you at the game. At the first sign of trouble they mysteriously vanish."
Synonyms: Bandwagoners, Best Fans in Baseball, Cardinal Nation, Faltering Followers, Fickle Fans, Mercurial Spectators, Mutable Enthusiasts, Redbird Nation, Unreliable Attendees, Vacillating Admirers, Volatile Aficionados.
In the News: "Attendance for Tuesday's St. Louis Cardinals game at Busch Stadium represented a record low for a night game at the venue since it opened in 2006, proving the fallacy that they have the best fans in baseball. When questioned by KMOX, the Cardinals, who are in last place in the National League Central Division with a 6-7 record, had no comment."
Example:
Joe embodies the essence of a fair-weather Cardinals fan. When they hit a rough patch, Joe not only publicly loses interest in attending their games but also secretly indulges in cross-dressing in Cubs gear and passionately cheering on the North Siders. 
