It's Always Sunny in Philadelphia (2005)

S18E3 The Gang Gets Tested

Dennis and Dee discover they both have ADHD, but the real shocker is that Mac doesn’t. Convinced they’ve been held back their whole lives by undiagnosed neurodivergence, the siblings decide to go back to school and relive their education with this new self-awareness. Armed with fresh insight and their usual chaos, they attempt to prove how much smarter they are now—though their “do-over” quickly spirals into a mess of missed deadlines, impulsive schemes, and misplaced confidence.