I've been rewatching TOS recently, and I noticed that Chekov's hair had a mind of its own for a while. I took a few screenshots, looked up the story behind it, and made this really quick for anyone like me who wasn't aware.
Roddenberry wanted Chekov to bring in the youth audience, so they gave him a wig to try to make him look like he's from the Monkees or the Beatles... absolutely hilarious.
Back when I was a wee kid, I loved watching TOS reruns. At that time Babylon 5 was first aired and my older brother was a huge fan. I remember walking into the living room one day during an epic crew roasting of Alfred Bester and not realising it was a different show, my first thought was:
"Wow, why's Chekov so mean all of a sudden?"