Fluffiest. (I discovered this morning that this isn't a word. But it's great) Well. It's sort of a half word. There are definitions in online dictionaries, but Apple doesn't recognize it and I don't think it's in a real dictionary. 
I think I was going to say something about this comment but I thought about it too hard and now fluffiest just sounds like a random collection of weird sounds and I've forgotten everything I was thinking. E: Just checked my dad's OED and you're right, fluffiest isn't there. But I came across another fun word - fluffily, meaning vaguely or indecisively.
I know exactly what you are talking about! That phenomenon is one of the more strange things our brain does. I think there was a name for it and some interesting factoids on Wikipedia but I can't recall the name right now.
Are you sure it's not a real word? http://news.sciencemag.org/plants-animals/2014/06/vampire-squirrel-has-worlds-fluffiest-tail