Disney Jail isn't really a jail, and it's not officially called Disney Jail. It's a room where rule-breakers are escorted and questioned. This video has interviews with three people who describe the circumstance leading to being taken to Disney Jail and what it was like being interviewed by Disney security.
One woman recounted the time her friend wore a tube top, which slipped off her chest during the waterfall descent on the Splash Mountain ride. Another man accidentally-on-purpose ate a hash brownie, began acting strangely and started smoking a joint in the park. A third guest yelled "Vote him out!" at the animatronic Donald Trump puppet in the Hall of Presidents.
The joint-smoker was banned for a year, the puppet-yeller-atter was given a warning, and the accidental flasher and her friend received candy.