When was the last time Hollywood gave us a drug dealer as a hero, as comic relief in a drama? It’s not something that happens often in a country where “Just say no” rivals “E pluribus unum” as a national credo.

But here is Harling Mays, lifelong pal of substance-abusing pilot “Whip” Whitaker, the comical candyman whose every entrance signifies emotional rescue, good times and “Just say YES” in the new drama “Flight.”

“Just say yes,” laughs Goodman, who plays Harling. “No way I’m owning that. Not something we want the kids to take up, is it?”

The “yes” phrase gets a laugh out of screenwriter John Gatins. He scripted “Flight,” which stars Denzel Washington as the pilot who acts heroically and saves many lives with an amazing bit of flying after his plane has a catastrophic mechanical failure. The guy flunks his drug test after the crash — big time. But Harling is the guy who can ease his pain, get his “edge” back — pharmaceutically.

“I don’t know if I’m glamorizing coke dealers, or even if Harling is a glamorous or cool character,” Gatins says. “Harling is exactly who he seems to be.” And who he seems to be, Gatins says, is Whip Whitaker’s true-blue friend.

Gatins is stunned by the reactions to this character, whom the Village Voice praised for his “dirtbag bonhomie,” whom Screen Daily described as the film’s “riskiest performance,” a jolly, bad-influence Falstaff to Denzel’s Prince Hal.

“I’ve seen the movie with a lot of audiences now, and the scene pops up where Harling is strolling down that hallway with a knapsack full of cocaine, riding to the rescue, people are cheering,” Gatins says. “It’s the strangest thing. I want to ask people, ‘Why are you cheering?”’

Credit the director, Robert Zemeckis, who scores Harling’s entrance with the Rolling Stones’ “Sympathy for the Devil.” Credit the screenplay, which sees Harling as an uncomplicated character in a movie full of moral ambiguity. And credit Goodman, the lovable big man who decided “Harling is stuck in another era,” and gave him the clothes, the shades and the ponytail — “Hair extensions, man. Two months. It was hell.” — to match.

“We all have that guy in our life we’re conflicted over,” says Gatins, a recovering alcoholic who combined “my two biggest fears — “drinking myself to death, and dying in a plane crash” for “Flight. “You kind of love the guy, but you don’t like what he brings into your life. He’s a bad influence, but he is the one person who says, ‘You need to go testify to the National Transportation Safety Board? I can have you out of here in seven minutes. You make the call.’ That’s who Harling is.”

Perhaps only Goodman, who like Gatins (“Dreamer,” “Coach Carter”), has had sobriety issues, could give Harling the credibility and lovability that makes the character work and whose contribution has helped “Flight,” which opened Nov. 2, become one of the most critically-acclaimed films of the year.

“If you’re a character actor, you spend some time thinking about your function in the story,” Goodman says. “You’re helping the director out when you do that, and you’re serving the story better when you know what it is your character does to move it along.

“Harling Mays is an easy out for Whip. He’ll tell Whip anything he wants to hear and supply him with anything he needs to get through the day. Starting with hero worship, building him up when he’s low, and continuing on through to supplying him vodka, cocaine.”

That’s part of the secret to Goodman’s success as a character player — that special breed of supporting actor who provides the exclamation point to scenes with the lead actor or actress, and sometimes steals those scenes. Goodman’s cool quotient stays high thanks to a steady gig, appearing in many of the tragi-comedies of the Coen Brothers, from “Raising Arizona” — “Still my best screen entrance ever, crawling up out of the earth and mud.” — to “Big Lebowski” and next year’s “Inside Llewyn Davis.”

And even without the Coens, Goodman is having quite the fall. He’s in “Trouble With the Curve,” playing a baseball team head scout sympathetic to a crusty, nearly-blind veteran of his scouting staff played by Clint Eastwood.

“My character, Pete, is a go-between,” Goodman says, laying out his “function” in “Curve.” “He wants to see his old pal and this new way of running a baseball team reconciled. He risks a lot to try to do that. He believes in old time baseball, so he wants Gus, Clint’s character, to succeed — be vindicated.”

And as John Chambers, he is the Oscar-winning makeup artist and comical-cynical Hollywood insider who helps the CIA set up a fake film production to free Americans trapped in Iran in the critical and box office smash, “Argo.”

“John Chambers’ function is being the guy who knows Hollywood,  the guy who jokes about the business, but knows the business, explains the business to the CIA and the audience. And he’s willing to get mixed up in something most people will never find out about.”

Gatins says that Goodman, like Washington, masterfully puts flesh and blood on a character designed to create unease in the audience for “Flight.” Could a sober man have cooly made the decisions that saved lives on this doomed airliner? And is the guy who keeps this addict functional merely an enabler, or the source of the edge that pilot needs?

“I want everybody to head into that last turn in the movie going, ‘I don’t know WHAT I’m rooting for here, or who,'” Gatins says. “Do we blame them, or let them go? The characters might seem evil, on the surface. But are they?” Washington and Goodman, Gatins says, give audiences inclined to see such characters in stark terms — “pause. And that’s what I hope people are arguing about when they leave the theater.”