Get a pack of sigs, smoke a few like when you're sitting at the table or something and pretend you're doing nothing out of the ordinary. If they start something, bring up the facts.
1) Where would he get some? Monkey's not 18, gotta be 18 to buy some. Though that's not a hard problem finding an 18+ year old kid to buy some.
2) To be honest, I wouldn't touch a cigarrette. :/ He'd also need someone to tell him how to smoke it. Yes, there's a right and wrong way to smoke them. Yes, I know a little bit but that's because one of my friends smoked and one of my other friends asked if she could light the cig for the smoking friend but the smoking friend said you gotta breath in at the same time and my other friend didn't want to actually smoke it, just light it for her smoking friend. (I have weird friends. x-x)
--This is an kind of unimportant little detail, but whatever.
3) What happens if monkey likes it? Sure, it sounds gross and he sounds against it, but you ever heard the whole "Once you start it's hard to stop"? That's what I'm worried about. Honestly, even one cig's bad for you.
It depends on what your dad likes about smoking. Does he like the nicotine in there? Or is the idea that he's putting smoke into his lungs? If it's just the nicotine rush, get the patch. People are still making them, obviously someone buys them.
I'm not sure of the side affects, there's pry something, but it's better than killing a lung. If anything, maybe if you get him on the patch, he'll stop smoking, and sooner or later just not want the patch anymore.