Refuge of the Damned is a secret location inside Springfield Elementary School, which nerds use to escape bullies.
Bart recently has a trip to Hibbert Moneymaking Organization, which results in him look like a nerd. At school the bullies attempt to beat him up, he manages to escape. While he runs a hand pulls him into a locker. It is Martin Prince. They go through tunnels into a room where many nerds are doing things that may result in beatings. they welcome Bart to their secret location.