"This is a totally unregistered cross-temporal asteroid. Here they can romp and play with other Jerries, it couldn't be safer!" -Rick to Morty
Jerryboree first appeared in Mortynight Run, as a daycare for Jerries. Rick and Morties are required to fill out a paper including information of their Jerry, including their original dimension,their allergies,length of stay, and reason for drop off.
Jerries are then taken to a room of other Jerries, decorated with golf courses, tunnel slides, and a miniature Titanic 2 model. However, the scenery doesn't seem to appeal to Jerries dropped off here, as most of them wander around, confused. Part of the Jerryboree is a slide that drops into a ball pit into a room that resembles the interior of the Smith House. It is said by the employees that it is an exit, but it simply leads to said room. In the "living room", an employee in a Beth suit tricks the Jerries to watching Midnight Run to make them forget what they're doing.
A secret room is located in an undefined place, containing Jerries whose Ricks and Morties never came back. The Jerries there fit this description as well, with some having a shaved head, smoking, and even simply laying on the ground. The entire room is run down, with stains everywhere and torn wallpaper.
Although there are many Jerries in this room, it turns out they can leave anytime they want, but they don't, because "they're Jerries".