I think this qualifies...

I was at the McDonald's drive-thru this afternoon (yay Monopoly!) and ordered a couple meals and fries for my family. We get to the window and the drive-thru person hands me my drinks, then a bag of food and says "have a good day!" I pull forward and ask DH to check, and it turns out we didn't get any fries.

I park and go back in with my receipt and bag to show them we didn't get fries. The front counter girl apologizes and says she'll go get them. As she leaves I see another guy go up to the drive-thru and ask what that extra bag of fries is doing there. The drive-thru person said "oh, those were that one lady's, but the idiot pulled away before I could give them to her" The guy points at me and goes "she's here asking for them." I just sort of gave her a look and she turned away.

I don't know, maybe it's just me, but when someone says "have a good day" at the drive-thru the transaction is usually over. And to call me an idiot is just icing on the cake.