Hair

 Where does Bart Simpson's face stop and his hair begin? It's an age-old question, but it was actually solved by the good people of Entertainment This Month, way back in early 1990. Here's their advert that appeared in American comics dated June 1990 (and actually published a couple of months earlier):

They sell comics, and T-shirts, posters and games based on comics. Comics are cool. But there's a new TV show that they're selling merchandise for as well...

Now, the Simpsons was brand new at the time, if you weren't one of the people who'd watched the Tracey Ullman show. You can tell how new they were by the fact that all the merchandise is based on Bart - that was something that didn't last long, before he was supplanted by Homer. But even so, the person who got the job of colouring this advert doesn't seem to have picked up on the colour scheme - they must have seen the bright yellow, because that's the colour they've given the Simpson kids' hair, but they've clearly decided that the characters' skin is actually supposed to be pink, and made an executive decision about which bits are skin and which bits are hair!

I like seeing artifacts from the days before a thing was common knowledge. Relics of ancient history!