I'll have your job for this

I was on 17 today, obviously. The register lived up to its reputation of being a harbinger of doom. Before I go any further with this story it is important to describe the setup of the register. I stand facing my register. To my right are all the packs of cigarettes, behind me are the cartons and to my left are the miscellaneous cartons that do not fit on the shelf behind me. A very grumpy old man with hair on the sides of his head, but not the top came through my line and asked for a pack of Marlboro Menthol Golds. I turned right and scoured the shelves. I couldn't find it and I do not blame myself because I don't smoke, it's a lot to keep track of and I generally assume people are capable of pointing to what they want. He sighed loudly and rolled his head sideways.
"It's right there; you don't have it," he said pointing to an empty row of cigarettes.
"Oh, okay. I have to ask a manager before opening a new carton," I said. I put my light on and waited for someone to come over. A second later Cam was there.
"Can I open a new carton of Marlboro Menthol Golds? We are all out," I said.
"Yeah," he said.
To save us all the trouble of waiting for me to find the carton I asked Cam, "Can you get that for me please?" Meanwhile the old man was glaring at me. Cam started looking through the miscellaneous cartons and eventually emerged from the boxes saying, "I'm sorry sir I think we are all out."
"Well that's just great," the man said in a tone that suggested he did not think this was great at all. It was right as he said this that Cam turned his head to the right and noticed there was a carton of Marlboro Menthol Golds out on the shelf already.
"Oh, I'm sorry, I didn't see those," Cam said and started opening the carton.
"I'll have your job for this," the man said, looking right at Cam. Even though he said it in a serious tone I knew he was joking because, well, nothing happened.
"I'm going to make sure you're fired," the man continued. I stopped and looked up at him. Apparently he was not joking. His head was actually shaking in rage. Cam and I looked at each other and continued smiling because this was all just so ridiculous.
"I'm an old friend of the manager and I am going to tell him what you did. You can't work here after this; you're incompetent. There's no way. You are going to be fired, I'll make sure of it."
As he went on with his rant I stood there stunned with a grin frozen on my face. I felt awful as I saw Cam's face turning red and he said, "It was a mistake sir."
The man would not hear it. He repeated, "You are going to be fired." He stared right at Cam and raised his eyebrows as if for a response.
"I'm sorry sir," Cam said.
"No you're not. You don't smile and laugh when you're sorry," he yelled. At that moment I was glad he wasn't looking at that grin still stuck on my face. Cam handed me the cigarettes. As he walked away the man called after him, "You're done here. You can be sure of that." He handed me a twenty without a word and I gave him his receipt and change.
"Thank you, have a great day," I said avoiding eye contact.
"Thanks you too," he said and left.