Cashier Experience

I hate cashiering. Is that even a verb? If not, we're making it one. It's so boring. I just stand and scan. Worse is when someone wants to pay with cash or a check. A check, who even shops with that? It's more annoying  than amusing. At least stupid customers amuse me and reaffirm my belief that forced sterilization is the right path forward for us as a human race. But, once in a blue moon,we get someone so stupid, you just want to beat them before they can hurt anyone else.

A guy comes up, wants to make 3 separate purchases in cash.I have no idea why but it just makes things take longer and when there's a line, no one's happy. So I ring each purchase up (there was only one item in each purchase, which I'm sure frustrated at least one other person besides me), take his cash, give him his change and give him his receipt. For some weird reason, he decides to put his 3rd receipt in the bag. Then he turns to me and asks where the receipt it.
"Right there in your bag." I grab the receipt out of his bag, show it to him, then put it back. "You put it there."
"I didn't put it there." He said, completely oblivious to the fact that he did.
Of course you didn't. It magically appeared there. So, he left and I continued checking out people out. Then he comes back after 5 minutes and say that I didn't give him the receipt, despite the fact that he not only saw me put it back in his bag but he also made it out the door with it. I told him that if he wanted another receipt, he'd need to go to customer service to rectify the situation because our registers don't store receipts. So he goes and comes back with the customer service worker.
"This man says you didn't give him his receipt." The worker told me.
"I did give it to him. I handed it to him, he put it in his bag without realizing it. I showed it to him when he asked where it was."
"Ok, just be sure to give receipts back to people." The worker said after searching my work area for a receipt that wasn't there. Of course this is all my fault. My bad. I clearly should've noticed that this man couldn't handle something as simple as a receipt. Next time I'll be sure to walk him to his car, cradle his balls if he asks, and be sure to call child services so that his kids can be raised by parents that are smarter and more sophisticated, like wild wolves.