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.

Whenever a region's sports team suddenly gets really good really quickly, everyone and their fucking dog either buys a sports jersey or takes their old one out of the closet where it's been for 20 years, proclaiming they are a diehard fan. Bandwagon fans usually flock to their team's games in large numbers and usually constitute 80% of that team's fanbase. See Florida Gators.