'Billions' star David Costabile on how he takes care of Wags' signature mustache, and what people yell at him on the street

Showtime

David Costabile as Mike "Wags" Wagner on "Billion"

• David Costabile, who plays Mike "Wags" Wagner on Showtime's "Billions," revealed to Business Insider how he takes care of Wags' signature twisty mustache.
• "There's a double dose of waxing a day," Costabile said - and he does it all himself.
• "It's got to be Wags length," he added.
• He also revealed the fan reaction after the first season aired when he knew that "Billions" would be a hit.

Mike "Wags" Wagner, the loud-mouthed COO of Axe Capital on Showtime's "Billions," has one of the best mustaches on TV, and it's especially known for its curl.

The actor behind Wags, David Costabile, revealed to Business Insider that to get the perfect "Wags mustache," it involves a lot of waxing.

"For the twisty mustache, there's a double dose of waxing a day," Costabile told Business Insider while promoting his cameo on this week's "Better Call Saul." "There's a wax in the morning and a wax throughout the rest of the day. Two separate waxes."

And Costabile does it all himself.

"I'm in charge of the 'stache and the goatee," Costabile said. "They're precisely measured and calibrated. Can't go too far, can't go too small. It's got to be Wags length."

"Billions" wrapped up its third season in June, and Showtime has already renewed it for a fourth season. It follows U.S. attorney Chuck Rhoades (Paul Giamatti), who turns his sights on the arrogant Wall Street billionaire David Axelrod (Damien Lewis), who he suspects of insider trading and bribery. Wags is Axelrod's right-hand man at Axelrod's New York-based hedge fund, Axe Capital.

When asked how often "Billions" fans approach him in New York City, Costabile said it happens a lot on Wall Street and at Grand Central. But there's one fan reaction in particular that sticks out in his mind. After the first season had aired, Costabile said that a garbage man in his neighborhood shouted enthusiastically at him.

"A guy collecting garbage was driving by in my neighborhood and he leaned out and yelled, 'Yo, I love your f---ing show, you're the best f---ing character on TV!'" Costabile said. "At that point I was like, 'Wow we've got a hit. When this guy is screaming out at Wags, that's when you know.'"