From the current issue of Overworked Photographer:
Your family doctor refers you to a dermatologist to look at a lump on your thumb, the dermatologist pokes and prods and studies the lump with a fancy loupe, and concludes that he knows the answer.
And that answer? You have a large callous on your thumb from the dozens and dozens of times you lift and reposition your tripod every day, which rubs an edge on said thumb and said area, and has turned into a gorgeous, impressively manly callous.
So I guess I’m claiming “photographer thumb” as a thing. I blame Planitar.