Something, especially referring to an event, that is
casually violent or chaotically aggressive; everyone involved has a
reckless, devil-may-care attitude towards the (often serious or important) problem or topic at hand.
Popularised by the band
Cage The Elephant, with their song 'Portuguese Knife Fight'.
Zach Casualrapeford: Hey Brock, you seen
Barron around?
Brock Chesterwood: Yeah bro, it turns out Ashley reported him to the principal about him raping Stacey. He said he was going to
have a word with her and her boyfriend, but he looked like he was gonna get into a
Portuguese knife fight instead.
Zach Casualrapeford: I hope he sorts that mess out before his parents find out.