She thinks she's funny, but she's not

I have a really good friend who is an English professor. At the end of each semester his students fill out (an anonymous) teacher evaluation form. One of the reasons the evaluations are done anonymously is so that the students can give an honest appraisal of the teacher's strengths and weaknesses and not be worried about a bad grade or "retaliation" from their teacher if they say something negative about the teacher or the class. On one of the evaluation forms one of his student's said, 'He thinks he is funny, but he is not.' Luckily, with his sense of humor in tact, my friend laughed and said he was going to frame that evaulation. But, I digress. Sometimes I think being a customer is sort of like giving an anonymous teacher evaluation. A customer thinks they can say whatever they want because there is a certain degree of anonymity in being a customer. If a customer is frustrated or upset about something, they sometimes feel like they can be nasty, yell, or vent their frustrations because the person working behind the counter (or at the restaurat or at the cash register) doesn't really know who they are. The customer knows they will very likely not run into the person again very soon so they say whatever they want. The other day a customer came through my line and her bill was $142. and change. She gave me a $100 bill and put the rest on her credit card. When a customer makes a "split" payment like that, our system (which is slightly outdated) will print out the credit slip for the customer to sign and then the receipt will print out and then the cash drawer will open (please notice the sequence of these events). So while I was waiting for her to sign the credit slip and waiting for the cash drawer to open I set the $100 bill down in front of me on the conveyor belt. She looked down at the cash and then looked at me and said something like, "I hope that $100 bill ends up in the cash drawer and not in "some one's"pocket." And she laughed. At first I sort of laughed...and then I thought about what she had just said. I admit it was a delayed reaction but the more I thought about it I was like, wait...what?!? I couldn't help but be sort of insulted. Did she just insinuate that I would pocket the money--and therefore that I was some sort of petty thief? And what did she think--I was going to pocket her $100 while she was standing right in front of me and then what? Was I gonna make a run for the border and live like a queen in Mexico with $100? I couldn't help but wonder would she have said something like that to a friend? Would she say that to a neighbor? Would she say that to a co-worker? And did she really think she was being funny? If she was trying to make a joke, I sure as hell didn't get it. So to borrow the comment from my friend's teacher evaluation--She thinks she's funny, but she's not!