Yesterday my co-worker told me how she finished ringing up a customer and then handed them the receipt and said, "there you go! You're all set!" and the woman stood staring at her. My co-worker was a little weirded out and tried some other cheerful phrases to indicate that the transaction was over and the woman could step away from the counter. But she kept standing there, staring.
"Was she drunk?" I asked my co-worker.
Then the customer said "I'm waiting for my thank-you" at which point my co-worker said "oh yes, thank you."
This particular co-worker is one of the sweetest, most pleasant and gracious co-workers ever. She exudes cheerfulness and genuine care. So to have some grump force a thank you that she didn't purposefully with hold is pretty insulting. Sure, a thank you was in order, but by being a jerk about it, the meaning was lost.
Take your fucking thank you, collect them like bazooka joe bubblegum wrappers, send in for the prize, and be disappointed when you realize it was all an illusion of hope and delayed pleasure.