S1E4: M. Night Shaym-Aliens!

In "Rick and Morty" Season 1, Episode 4, titled "M. Night Shaym-Aliens!", Rick, Morty, and Jerry find themselves trapped in a simulated reality created by the Zigerion aliens. The Zigerions are trying to extract Rick's formula for concentrated dark matter. Rick quickly realizes they're in a simulation and tries various antics to throw the aliens off their game. Meanwhile, Jerry, blissfully unaware of the simulation, experiences an inexplicably successful day at work pitching an advertising campaign for apples. As layers of the simulation are revealed, it becomes clear that Morty is also a simulated version, and Rick hatches a plan to outsmart the Zigerions. Eventually, Rick tricks the aliens into thinking they've successfully obtained his formula, but it's actually a fake recipe that causes their spaceship to explode. In the end, Rick and Morty escape back to Earth with the real Jerry still oblivious to the whole ordeal. Back at home, Rick gloats over having outsmarted the aliens while Morty is left exasperated by yet another chaotic adventure with his grandfather.