One of the interesting consequences (well, to me anyway) of shaving my head is getting to know it's general geometry.
Turns out I have a sort of weird indentation on the left that means I sometimes miss some tricky hairs.
Who knows what crazy fissures and ridges exist on the back of my head - that I just do by feel, so don't really notice the dents as much.
As an aside, I just realised it's phrenology and not nephrology that's the study of bumps on the head (others have had the same confusion). Tricky anagrams!
[Image credit: Stuart Rankin]