People who are
friends/meet up for the sole reason of going to events, concerts, festivals, or gigs, often due to real
friends (or lack of real
friends) not sharing the same taste in music or said events, concerts, festivals, or gigs.
Often, people looking for "gig buddies" conjugate online, in places such as Last FM, to find others who share similar musical tastes, and as such are willing to go to events together, despite being complete strangers.