The Joker #1 gives readers a huge tidbit about the Joker's hideout: he has a security lock that's tuned to his unique laughter. Without the Joker's laugh, no one can get into his base. It's later ...
It's not like the Joker's hideout is just a warehouse with a fancy name either; the Joker's security systems for the Ha-Hacienda are surprisingly sophisticated, even rivaling those of the Batcave.