It’s the kind of thing that comes to you in the depths of a raging fever: a man with a crescent moon-shaped head, dapper tuxedo, and sunglasses playing the piano while perched on top of a two-story-tall hamburger.

His name was Mac Tonight, and he emerged from brainstorming sessions at the ad agency of Davis, Johnson, Mogul & Colombatto (DJMC). McDonald’s franchisees in Southern California had come to the firm in 1986 complaining of stalled sales at their restaurants, particularly during dinnertime hours. McDonald’s national campaign, a $550 million annual venture handled mostly by the mammoth Leo Burnett agency, was relying on nuclear families and the familiar, painted face of Ronald McDonald. For many operators, though, it just wasn’t working.

Brad Ball, president of DJMC, and creative director Peter Coutroulis weighed their options. Ball was incredibly fond of “Mack the Knife,” a tune first written for a 1928 German opera and popularized by singer Bobby Darin in 1959. He listened to Darin’s version over and over, along with covers by Frank Sinatra and Liberace. The song was close to being perfect for McDonald’s, he thought, but it needed some kind of twist—something that would stand out.

At the time, Max Headroom was an advertising and cultural phenomenon, a bizarrely-sculptured character sporting shades and exaggerated features. Eventually, Ball and Coutroulis settled on the moon-faced Mac Tonight, a hipster crooner existing in a weird dreamscape who could appeal to adults and reinforce the idea that McDonald’s was the place to be after hours.

DJMC hired actor Doug Jones, a lanky performer who later appeared as Abe Sapien in 2004’s Hellboy, and shot a series of commercials intended for the Los Angeles area. The tune to “Mack the Knife” stayed, but the lyrics were tweaked:

When the clock strikes / half past six babe / time to head for golden lights / It’s a good time / for a great taste / Dinner at McDonald’s / It’s Mac Tonight!

The four spots began airing in late 1986 throughout California, Oregon, Las Vegas, and Phoenix. The segments, which cost a total of $500,000 to produce, were abstract, jazzy, and a far cry from Ronald McDonald’s Technicolor adventures: Mac soared through clouds and even in space, passing a "big dipper"—a McNugget with sauce. The campaign caught on immediately, with some restaurants in California reporting a double-digit increase in sales. “Mack the Knife” was familiar to baby boomers, a demographic the brand wasn’t used to courting; the fresh take was paying off.

At a national franchisee convention the following year, operators crowded around monitors to get a glimpse of Mac; in-store appearances from employees wearing a fiberglass head drew crowds of up to 1500 people. (Anticipating kids clamoring for a piece of Mac, the glasses were held on with Velcro.) As word began to spread of his impact on the bottom line, McDonald’s headquarters in Oak Park, Illinois took notice. This crescent-brained singer could have national appeal.

On August 21, 1987, Mac arrived at a Boca Raton McDonald’s in a limo. Strutting out, he was hoisted to the restaurant’s roof, where he sang, danced, and played the piano. “I describe him as a cool dude,” said Anita Fraunce, a McDonald’s marketing manager. The corporation dismissed the idea that “Mack the Knife,” ostensibly about a murderer, was inappropriate for fast food ads. “The lyrics are well known and the song merely symbolizes the music of the ‘60s,” said national marketing vice president David Green.

Mac’s appearance in Florida was the official launch of a national advertising campaign. For six weeks, Mac's ads were in heavy rotation across the country. Viewers wondered whether Sammy Davis Jr. was doing the singing. (He wasn’t, but the company never revealed who did.) Big Mac sales reached record highs; one company representative teased that Mac would never again be seen after October.

Of course, it was a bluff. Mac’s inaugural ads were so successful that Jones was hired to do a total of 27 spots; toys began popping up in Happy Meals. That fall, Mac was pegged as one of the most identifiable brand characters in the country. Word was that the moon man could finally be the mascot to fill Ronald’s sizable shoes.

But Mac’s run at the title would prove to be short-lived. In October 1989, the estate of the late Bobby Darin (he died after heart surgery in 1973) sued McDonald’s, claiming the company had appropriated Darin’s “style” without permission. They asked for $10 million in damages. While the Darins wound up dropping the suit [PDF], the proceedings stalled out Mac’s astral trips.

The character reappeared briefly in 1996 and 1997 before largely being relegated to McDonald’s memorabilia collectors. While a version rendered in CGI sometimes appears in foreign ads, his profile in the States has been virtually erased. If not for the Darin family’s litigation, perhaps Mac could have gone on to change the course of fast food advertising forever. As it stands, we’ll never know who the true burger king could have been.