A person completely obsessed with the rock band My Chemical Romance, knowing most of their lyrics, lots of thins about them, the full names of all the band members and other projects they have, when will they do a show, secrets about their childhood, etc.
Example Nº 1:
A: *walking down the street when hears "Dead!"* OOOOH MY GOD OH GEEZ
, OH MY GERARD, DEAD! I LOVE THAT SONG!! *starts singing it*
B: damn you're such a chemicaler....
Example Nº 2:
A: What's your favorite MCR member
....no, wait, Mikey
...No wait WAIT Ray!! GEEZ I can't choose one of them, are you out of your mind?
Not the best examples, but well........I'm a chemicaler XDDD