Of Course I Smoke

Someone who doesn't smoke is, for whatever reason, trying to act like he does. He lights the cigarette, takes a big drag and...

COUGH COUGH COUGH GAGGHHHH!

This, of course completely ruins the act. Most commonly done by teenagers trying to look cool, but sometimes done in order to maintain The Masquerade. Compare Of Course I'm Not a Virgin.

Examples of Of Course I Smoke include:

Anime and Manga

In Monster, the 9-year-old Dieter tries to impress a bunch of men at a bar by entering smoking a cigarette, ordering a drink, slurping it up, and leaving the bar. Once outside, he rushes to an alley to cough and puke, wondering why adults do those things.
School Shock: Hao Xuan went through hard times, and tries calming down with a smoke - it ends as expected. He still pulls it through, though.
In the 12th Detective Conan film Jolly Roger in the Deep Azure, Takagi tricks a Genre Savvy suspect into giving him his fingerprint via asking him for a light and pocketing the matchbook the suspect hands him.

Sato: Takagi, when did you start smoking?
Takagi: *HACKHACKCOUGHCOUGH*

Film

In Thoroughly Modern Millie, Millie does this to act casual outside of a Chinese opium den. It didn't end well.
In The Legend of Zorro, Elana gets rid of Armand so she can talk to Alejandro by asking him to buy her a pipe. Much later, after she and Armand have had dinner, a servant brings "her" pipe. Initially she says she needs her stomach to settle first, but when she needs an excuse to be out on the balcony, she's forced to light up.

Armand: Are you all right?
Elana: Fine.
Armand: My God, you're turning green.

In Smokey and the Bandit, Sally Field's character, Frog, takes up smoking the Bandit's cigarettes, and is obviously a non-smoker.

Bandit: "I think you should give it up." (referring to the cigarette on which she's choking)
Frog: "But I enjoy it so much..."

Literature

In one of Isaac Asimov's Black Widowers stories, the guest specializes in job interviews, and he relates the story of a man who nervously lit up in the middle of an interview, suffered a coughing fit, and admitted that he really didn't smoke—he was just trying to look cool. Of course, the job went to the other candidate. However, the Black Widowers deduce that the man was an ex-smoker who staged the scene in order to force the interviewer to choose the other candidate; they were accomplices in a plot to embezzle money from the company. He faked the coughing fit, but forgot to conceal the fact that he could light a match with one hand.
The first time Pudge smokes in Looking for Alaska he tries to act cool about it and then nearly coughs up a lung, though he ends up smoking pretty regularly.
In the The Hunt for Red October, Jack Ryan was an occasional smoker (smoke for a while, quit for a while, but never more than two or three a day at his worst.) Jack Ryan tries to break the tension of the initial meeting between Americans and Russians by bumming a smoke off the Russian engineer. He immediately begins coughing, fortunately, this provides the levity needed to break the ice. The Russian cigarette was described as "like smoking asphalt through a cardboard tube."
- Done intentionally in The Movie of the Book. Ryan takes a few puffs, he starts coughing, and the engineer says, in Russian, "He's turning green!"
Esme Squalor in A Series of Unfortunate Events is obsessed with what is "in", and in the 10th book smokes what she thinks are cigarettes (they're actually flares), and despite bluntly stating she hates the smell, taste, and the fact that they're bad for you, she remains on the hunt for more to smoke which the Baudelaires use to bait her.
Happens with the female journalist Raffles hires to help run his sporting magazine in "The Raffles Bombshell" by Barry Perowne:

"She made out that she smoked Sullivans, Like Raffles, but I knew this was just a gesture of emancipation, as cigarettes made her cough."

Live-Action TV

Greg did this in The Brady Bunch. Ironically, Barry Williams (who played Greg) had just quit when they did the episode, which made him start up again.
The old Batman TV show used this when Robin/Dick was trying to infiltrate a gang of "Delinquents".
On The Wonder Years, in an episode where the Arnold family goes on a vacation at a lake house, Kevin tries to flirt with a girl who smokes that he just met by showing that he smokes, too, resulting in a coughing fit.
On Seinfeld, George tried this to get out of the planned marriage with Susan. It doesn't work, either.
In an episode of Friends, Rachel tries to take up smoking because her boss and other assistant make all their decisions in the smoker's lounge. She is not successful.
In the Small Wonder episode "Smoker's Delight", Jamie experimented with tobacco in hope of becoming more popular as a freshman in junior high school.
Donna does this in the first season of Twin Peaks. Apparently she's the only person in her high school who doesn't smoke.
In Frasier Niles ends up pretending that he came outside to smoke, too embarrassed to admit that he and his brother couldn't get tickets and are waiting for them in the cancellation line.
Captain Picard in the season one episode "The Big Goodbye", during his first time on the holodeck as Dixon Hill. He takes a drag on a cigarette very suavely, and then chokes and puts it down. He may have become more accustomed to smoking, though, because later on in the series he smokes as Hill again, with no trouble.
In Breaking Bad, Walter White bums a cigarette from Jesse Pinkman in an attempt at conviviality. It's obvious he's never smoked a cigarette in his life.

Newspaper Comics

In Calvin and Hobbes, Calvin tries smoking a cigarette. At the end of the strip, Calvin comments that it was trusting parents that caused him to smoke and therefore damage his health.
- It should be noted that his mom knew this trope was coming and let Calvin smoke in order to teach him a lesson.

Web Comics

Syrus "the Virus" in Exterminatus Now did it on the cast page. Discussed on the next page:

Harold': You mean it was a lame attempt to look like a badass.
Syrus': Did it work?
Harold': Nah, you just looked like a regular ass.

Dominic Deegan does this to himself. He lights his pipe, inhales, and... discovers that when his white mage brother Gregory healed him earlier, he also cured his smoking habit.

Web Original

The Nostalgia Critic attempts a moment of suave smoking during a parody of The Twilight Zone, only to collapse in a coughing fit.
- But subverted and justified in his review of Double Team, where he lights up a cigarillo in celebration of the film's climax. Cigarillos are classed as healthier than cigarettes, as you don't inhale, you just keep the smoke in your mouth and breathe out.

Western Animation

On The Simpsons, Patty and Selma are caught smoking at work and are about to be fired when Homer, in an uncharacteristically gallant mood, claims the cigarettes are his and smokes them, claiming between coughs and gags that he is "in flavor country".
- Another time, Marge (a nonsmoker) claims she "just felt like filling the house with the rich, satisfying smell of tobacco." She's trying to overwhelm the smell of the chili cookoff so Homer won't go to it.
- Also happens with Ned Flanders as he and Maude play hippies in a fire safety play. Though his cough from smoking is the least of his problems as he inadvertently sets his pants ablaze.
On Futurama, Kif does this, causing incredible reactions from his alien body.
In the Cleveland Show Tim the bear becomes an evil boss so Cleveland has to smoke to get a break.