I've noticed the "bump" on the back of my head since i was younger. When I use to shave/buzz my head, they'd (my friends) call it, the "knob"
I've noticed few people have one as large as mine, but none the less, it's still fun when I go to ABC Hair Cut place, and the new girl is all
suprisied about this, "bump on the back of your [my] head."

Nice to see im not the only one with the big knob.
ps. people with big knobs are smarter.