Oola hated that the rancor was kept caged below the throne room. At night she used to sneak down to the kitchens, steal some meat and go and feed it to the rancor. She and it were both slaves to Jabba
When the time comes and she is fed to the rancor, it remembers. Instead of chewing her up it pops her in its mouth and stomps back to its den. Oola spends a very unpleasant few hours skulking in its mouth, trying not to choke on its terrible breathe. After a while it’s let out into the yard to run around like a free range rancor, and spits Oola out. The fence was made to keep rancors in, and its childs play to slip through to freedom.