Can't be easy to remember, for sure, since many of us have many matches almost every day. I've gotten tons with Ganondorf, since I play him 99% of the time, but as far as I remember right now, I think the most disrespectful KO I've ever gotten was a few months ago.
I was playing Ganon, For Glory, VS a Marth. I got a very long Flame Choke chain, ended it with a pivot Side Tilt, sending him off-stage. Then I remember turning away from the ledge, Side Taunting (where he slams his fists against each other), before jumping backwards off-stage and spike him with Down B. So... very... satisfying...
I was playing Ganon, For Glory, VS a Marth. I got a very long Flame Choke chain, ended it with a pivot Side Tilt, sending him off-stage. Then I remember turning away from the ledge, Side Taunting (where he slams his fists against each other), before jumping backwards off-stage and spike him with Down B. So... very... satisfying...