A term commonly used (especially around Hillsboro, Missouri) to describe one's excitement about a certain event, object, or situation. Similar to the phrase, "that's hot." The meanings are similar.
Corey: What up pimpin?
Trevor: Nothin big worm, just snatched up some BL for a lil pong action tonight.
Corey: Aw yea, that's my boy. I twisted up some phillies too.
Trevor: Fuck yeah, "that's fire" bra!