Most common in sports, a bandwagon fan is a fan of a team simply because they are the reigning champions/have the most championships/doing the best at the moment. The second these fans notice that they're team is starting to do poorly, they'll jump ship and hop on the bandwagon of a different team that is doing well. As a result, they will have little to no knowledge of their current team and the true fans of said team will hate them for it.

Bandwagon fans are typically fans of the New York Yankees, Boston Red Sox, Dallas Cowboys, New England Patriots, Miami Heat, Los Angeles Lakers, Duke basketball, and Alabama football.

Anyone who claims they are a "fan" of a particular sports team, even though they had no prior support for/interest in the team until that team started winning. These types of fans only show playoff interest, have probably never watched a regular season game, don't own any type of team merchandise, nor would they buy any.

A fan who starts cheering for a team once they start winning. Has particular interest in one particular star player and probably doesnt have any of the team's merchandise

Anyone who became a Miami Heat fan in 2010-2011

The reason why tickets are higher when the team is winning

A person who becomes a fan of a sports team just cause they're the "newest hit" or "big thing". Also almost all of the Golden State Warrior fans. Want to be saying "Go Golden State!", Just because they're 23-0 and because they won the 2015 NBA Finals.

A disgraceful sports 'fan' who roots for a particular team (usually one that has constant postseason success) but knows nothing about that team's history, players, coaching staff, etc. In fact, the 'fan' probably didn't give two shits about the particular team until they started winning. The bandwagon fan makes the established fanbase of a team look bad and is often seen flaunting New York Yankees hats, Miami Heat jerseys and/or Alabama Crimson Tide gear. A bandwagon fan is usually someone who fails at life and cannot think for him/herself.