“It Pays to Advertise” overextends itself in every direction to get you to laugh — physical comedy, witty banter, slapstick, even some mild ethnic humour for good measure. And it works!

Directed by Stan Wojewodski Jr., the Yale Repertory Theater’s artistic director and dean of the School of Drama, the show doesn’t aspire to be more than what it is — a silly, happy, fast-moving farce.

Set in 1914 New York, “It Pays to Advertise” is the story of a generational war between the crusty-but-inevitably-lovable Cyrus Martin (Jack Davidson), the Rockefeller-wannabe head of the “Soap Trust,” and his goofy son Rodney (Adam Greer), whom everyone agrees “can’t be such a pinhead as he looks.” In an effort to make Rodney an upstanding citizen and businessman — more or less the same thing in this show — Cyrus cuts off his allowance. On a whim, Rodney decides to defy his father by launching an advertising campaign for a new competitor soap, Number 13 (“Unlucky for dirt”).

With help from his fiancee (also his father’s secretary), savvy Mary Grayson (Sarah Rafferty), the cigar-chomping tweed-sporting ad man Ambrose Peale (Michael McGrath), and a few loans, Rodney launches the business. Of course, his venture quickly turns from “the best game I’ve ever played!” to a serious cash flow problem. But in the process, wouldn’t you believe it, Rodney becomes a Man!

Given a ham-handed cast, the show’s less-than-subtle social commentary and sudsy-clean humor might be lame and annoying. The good news is, they’re not, so it’s not. As Rodney, Greer pulls off the jokes even as he makes the subtle transition from being a smarmy and spoiled playboy to an enthusiastic entrepreneur. Davidson was also a highlight, playing his hysterically gruff-but-loving role with a breathtaking lack of irony.

The only cooperative effort by largely forgotten Walter C. Hackett and Roi Megrue, “Advertise” was first performed in 1914. What must once have been credible now seems sweetly naive, as Cyrus Martin claims “You can’t fight the soap trust with advertising — we’re established.”

Indeed, the show’s attitude is so gung-ho that, were it written more recently, I’d be looking in the program for the names of its Madison Avenue backers. Otherwise, it’s hard to imagine now getting so lyrical and dreamy-eyed about “the power of suggestion — the psychology of print!”

But leaving aside social criticism, it’s amazing how the show now succeeds in making its point — the gee-whiz power of advertising — in a way that its original audience could not have experienced. It’s almost creepy the way virtually all of the “sensationalistically” advertised real-life brands mentioned in the show are still household names, including Kellogg’s Corn Flakes, Coca Cola, Wrigley’s spearmint gum and Ivory Soap (the lone competitor of the fictional Martin).

True, some of the jokes have aged a little bit. It may not be an urban paradise, but cracks about how dirty Pittsburgh is don’t zing the way they might have back when it was an icon of industrial grime. But the show makes you want to laugh anyway, just for the heck of it (and yes, this is a show that uses words like “heck”).