I suppose cigarettes are just too expensive these days, so the guy simply ran out and needed a nicotine fix. Normally bumming a cigarette wouldn't be a problem for him, since smokers are, as much as it boggles the mind, easy to find. And it should have been a piece of cake to "borrow" a cigarette from a complete stranger. But he just happened to pick the wrong stranger. I am likely paraphrasing, but the conversation went something like this:
Patient: Hey, can I bum a cigarette?
Stranger: Um, no.
Stranger: I said no.
Patient: Ok, I'm going to beat the shit out of you.
So the guy attacked the stingy smoker for not simply handing over a cigarette. What he didn't count on was the other guy being much faster than he. And having a knife. Not only did he receive multiple lacerations all over his body, he didn't even end up getting his cigarette.
We sutured up his lacerations and sent him home, after suggesting that he either A) quit smoking or B) quit attacking ninjas.