?
I think it is when two fighters have a grudge or dislike against each other maybe from having fought before or one having stole the others partner.
Just a bit of added spice to the match.....or maybe it's when some of the oldies around here fall out while at knitting classes :)
Both the academic dictionary and her slang counterpart point to a fancier expression for a catfight, as it's a conflict meant to inflict injury with malicious intent, that involves breaking the other's spirit.