I knew when I went into hairdressing that my feet would hurt and I might have to deal with some strange people. I was a bit surprised at how much wear and tear my hands had to take, and how much money people think I make. (To be clear, I do not pocket the entire sum you pay for your haircut.) But one of the things that did surprise me when I started hairdressing, is how strange and varied people's head shapes are. Seriously, you'd be amazed at how many peculiarly formed some people's heads are, and, here's the kicker, they don't even know themselves! They think their heads are perfectly normal. As do you, probably.
I remember shampooing one woman's head and, as my fingers moved to the back of her head from just above her ears, my hands were moving towards each other at an entirely impossible angle; her head was absolutely triangular. Like, I didn't know if she could ever sleep on her back, triangular. That occipital bone (that lump about half way down the back of your head) is supposed to run parallel to the ground, not perpendicular. It was like shampooing a block of cheese.
Another client I saw once had an occipital bone that stuck way out from her head, way more than was usual. She could easily smuggle a couple of ounces of pot under her hair and no one would ever notice.
Sometimes I would put my hands in someone's hair to run it into the basin, and lo and behold, their head looked normal sized, but it turns out they had ridiculous amounts of hair and a teeny-weeny little head under all that! It was like finding an egg in a bearskin rug.
I have one client that I pray never needs to shave her head, because her head is round enough, but so bumpy and bony, it would look like her head was molded out of clay by monkeys.
Occasionaly, you come across divots and troughs in people's heads, weird little dips and dents that are quite alien. Sometimes they are because of surgery, but mostly, their just because nature has a sense of humor.
I also had a client who's head was perfectly cubic. Like a robot. It was really easy to cut his hair, though, because all the surfaces were entirely flat. How he bought hats I'll never know.
Some heads are pointy, some are huge and some are really long from front to back. Luckily, nobody knows they have a weirdly shaped head until someone tells them. But I'll bet their mothers know.