2. A derogatory term for girls (or group of girls) such as bitch or cunt
"Oh man you banged her? You know she's a HUGE burner!"
"Let's go talk to those burners over there, they look hungry"
"That fucking burner wouldn't give me her number"
"After pnping all night, I think that burner gave me that die slow"
The word derives from that fact that a variety of art work is featured at all such events, and some of it (or much of it) is intended to be set on fire and burned to ashes during the event. Indeed, all burn events climax in the ritual burning of a large, wooden effigy and/or art edifice on the final night(s) of the event.
"Oh yah, I've been to Burning Man twice, as well as a couple local burns back east."