Wtf is "nappy hair"?

Is that even real thing?

I recently thought about how as a child I'd always hear jokes about nappy hair (pretty much used towards anyone not mixed or sporting 'baby hairs') and I was always just like
woo yeah haha. Niggers. 
But I didn't get it?

Because my family wasn't full of weird fucked up black people ( Well not in that sense Lolz) do it wasn't used in my home life. Just school.
Anywho. As an adult all I see is "normal" black hair from black people. All types of textures and types and colors and now I'm like "OMG, all those coons I went to school with were just brainwashed"

So, is it just that the word has a negative connotation to it? Because this is what Google brings up when I search nappy hair:

All I see is normalcy.

Guh, wut?