[Jaydelart]

I understand it can mean a form of love (different from the word 'ai' (愛)). I also understand it as a fish (鯉). However - and I'm somewhat embarassed to admit this - I've seen people use something that sounds very similar to "koi" on TV shows, as a way of beckoning before a fight.

Maybe it's ko-i...? I'd be lying if I were to say I was certain.
I'm not sure how to phrase my question properly... But can someone please explain this to me? Or am I listening to it wrong afterall?