There are many variations of the famously curved Handlebar, ranging from Captain Hook's split brow and Rollie Fingers's perfectly coifed curlicues to the Pringles guy's curved bush. How yours turns out depends on what type of hair you grow naturally, though smaller faced guys will want to shoot for the Petit Handlebar.
The first thing to know about handlebar styles is that they take time and have strange in-between phases. "Especially if you're going for the petit handlebar," says Decatur. It will start off looking like something a German dictator once wore, though you can tell people you're going for a Charlie Chaplin type of thing.
For the Petit, keep your mustache shaved off to the width of your nose. This patch will become the base of the handlebar. The goal is to grow that hair out long enough so that you will be able to shape it into a loop, which will likely take about four months. While that's happening, wet the whiskers and brush them outwards every day. They'll go back to their natural position, but after a while, they will be trained to go in the direction you want. Then, control the follicles with a bit of wax, placed between the index finger and thumb, by squeezing the hair the same way that you'd snap. Eventually, that motion will result in those classic face curls.
For the regular handlebar, do the same while working with a larger base. Place your finger vertically at the side of your mouth for direction. And that part in the middle? "That's actually natural on some guys, but you can imitate the same thing by turning your trimmer longways and dabbing in that spot," says Decatur.