Cracker-Choker, Bumbling Con Man

On my way through the service last flight, this guy orders an alcoholic drink. I ask him for the five dollars one of those things costs, and he asks to put it on his tab. I said sure, because a few folk had asked me to do that before, and what they usually do is order another one later and settle up all at one time when the second one arrives.
This was my first mistake... thinking the concept of 'tab' is universally understood. Next time, I'm gonna ask for a credit card just like they do at a bar.
On the way back past this guy, he chokes on some crackers and makes a big deal out of getting some water from us. Both of us FAs now know who he is. His first mistake.
About an hour later, the other FA says she's taking a liquor back to a guy. I ask, "The Cracker-Choker?" She nods. I explain that he's running a tab, and that if he tries to give her five more than for that one drink, then that's what that's for.
During taxi at the end of the flight, I remember that I didn't get any money from Cracker-Choker. So I call back to the other FA to make sure she didn't settle up with him already, so as to save myself from an embarrassing situation. She tells me that not only did he not give her anything, he told her he paid me.
His second mistake.
On his way out the door, I politely ask him to settle up. He tells me that he gave the other FA a coupon. I explain that that's funny, but she said you did no such thing, and let's settle up. He gives me that put-upon exhale, digs in his wallet, and gives me a five. I tell him no no no, that would be ten you owe me. I gave you a drink, she gave you a drink. Five each. Five plus five is ten. He looks in his wallet, then begins to tell me that he really did give the other FA a coupon, and no sir you didn't, I say, that'll be five more dollars.
He gives me the exhale again, and then a fistful of bills that, as I count, turns out to be four.
"Five dollars," I say. "This is four."
"That's all I got on me," he says.
"What you're telling me is that you can't pay for what you drank?" I say loudly, in front of all the other passengers waiting for their carry-ons.
"It's all I got on me," he repeats.
"You do know, sir, that I have to pay for whatever you can't come up with, right?" People stare. He begins to speak, and I know what he's going to say, so I cut him off. "Well, I hope you enjoyed your drink. Have a good night."
He shrugs lamely. "It's only a dollar."
"Like I said, sir, I hope you enjoyed your drink. Have a good night."
At first glance, it might seem as if this guy got over on me. But it was well worth one dollar to me to publicly harangue this guy for being a cheap thief. And he only got one dollar out of me... I cleaned him out.