Idea: Pentakill skins

I don't know if this has been suggested, but I think it would be awesome if there were a special skin for each champion that unlocks when you get a pentakill with that particular champ. I know there are pentakill skins already but I just mean special skins. Also if you collect all pentakill skins you get a crazy reward like an ultra rare-legendary skin or something. Just an idea. What do you guys think?