A rare bird. Any person who goes to a significant portion or whole tour of a single rock band's tour run and has the appearance (due to greasy hair and generally unkempt hygene) of a drowned rat. Generally found at jam band concerts (Phish,The Dead, Widespread Panic). Regarded with a mix of wonder ("What, do you have a trust fund or something?") and disgust ("No, I'm not giving you my ticket for free.").
Dude #1 "Jeez, check out the tour rat"
Dude #2 "Wonder how many shows he's been to..."
Dude #1 "Wonder how many shows he remembers!"