human_being1: Die in a fire.
Later in that same chatroom...
16yo_girl: AVRIL LAVRIGNE IS SO THE BEST ARTIST OF THE LAST 10 YEAR1111
human_being2: Stop yelling... and no, no shes not, her songs suck, for starters
16yo_girl: YEAH RIGHT11 HER SONG IMAGINE WAS SOOO DEEP111
human_being2: Die in a fire.
The term originally came about when a player was trapped in a temporary wall as he/she was burning. Evil Bastage member told him/her to die in a fire as he/she burned. It stuck from that point forward.
Evil Bastage: Die in a fire
Since then many have used it on the WoW forums. Also players carried it with them to other internet areas. Since then it has spread like wild fire on the internet.
Die in a fire is basically a "go kill yourself" but in a funner way. Use it to insult or to tell some one to F' off.
Lady: Go DIE IN A FIRE!
GUY: That cashier just ripped me off
GUY2: Dude she needs to die in a fire.