In this Improv Everywhere prank, people riding the subway run into their future selves, who have come in a time machine to give them a dire warning. Cool, right? Except, in reality, the whole thing is just a bunch of twins. F*cking twins—ya can't trust 'em. "We staged the scene five times total, all on the N train [in New York City]," wrote Charlie Todd, the founder of Improv Everywhere, in a blog post. "We took a break in between each staging so the crowd on the car would turn over."

Sources: Improv Everywhere