Like many of the best animated series, Smiling Friends revels in adult darkness while looking like it was made for kids. Even its name could sound creepy or wholesome depending on your mood.

The Adult Swim show, which is airing a special episode tonight, follows two Smiling Friends employees—sunny Pim and cynical Charlie—who, at the behest of their boss, Mr. Boss, are given a simple task: Make clients smile. The pair seem to have no training, and often encounter bleak circumstances: In the pilot, they attempt to cheer up a man who constantly holds a gun to his temple. By the show’s seventh episode, a rival company, Frowning Friends, has set up shop across the street. (“I get it Pim, they’re the bizarro versions of us, but what’s the endgame? It’s just pissing me off now,” complains Charlie). It’s much easier to make people frown than it is to make them smile, and the new outfit draws a crowd, promising to reveal “the brutal cruelties of reality.” Frowning Friends’ grotesqueries, however, turn out to be stock footage of military marches and burning trees. “Is this really supposed to be …” Charlie says. “I’ve seen way worse on the internet.”

To be sure, much of Smiling Friends’ darkness, and humor, comes from the internet. Animators Zach Hadel and Michael Cusack say that the show, and that joke specifically, are throwbacks to a time when the web felt unfiltered—when it felt scary and chaotic and thrilling. Smiling Friends is steeped in early and mid-aughts internet animation and humor, a time when colorful cartoons about bopping badgers spread like wildfire and kids had to install the latest version of Flash Player to keep up. When being 12 years old, says Hadel, meant going to your friend’s house and having them show you the worst video they could possibly find. When kids crowded around a computer and beat up a digital George W. Bush, and braved shock sites like Meatspin, Lemon Party...