Why do patients say "Thank you" to me after I take a blood test from them?
It's very nice to hear and all but I'm never quite sure what they're thanking me for. I walk up to them, I tie a band round their arm and then stab them with a metal needle with the intention of making them bleed.
It's not the sort of thing that you'd think a person would be thankful for but the "Thank you" is usually forthcoming afterward. It puzzles me.