21 Jump Street takes special pleasure in subverting expectations. Despite Ice Cube’s early instructions to “embrace your stereotypes,” Schmidt and Jenko end up embracing each other’s due to a careless mix-up on the first day of school, making Hill the cool kid and Tatum the nerd. And as they attempt to reinvent themselves on the fly, the duo become amazed to learn how much high school has changed. The drug dealers drive hybrids, no one calls each other on the phone anymore, and it’s no longer acceptable to exert your dominance by face-punching the first guy who looks at you funny. It’s a premise that cleverly subverts the movie’s reason for being: Just because you’ve done it before doesn’t mean you’ll know how to do it again.