A fizzy fruit drink that Guinan serves to young Clara Sutter in Ten Forward in the episode Imaginary Friend, offering a second glass for her invisible companion Isabella.
Papalla juice is a soft drink popular with children aboard the Enterprise-D. It appears in The Next Generation episode Imaginary Friend, set in 2368.
Clara Sutter, a lonely girl whose father is frequently reassigned, has invented a playmate named Isabella. When an energy being from a nebula takes Isabella's form, Clara is led into parts of the ship where children are not allowed, including Ten Forward. Guinan treats the trespass kindly, sits the girl down with a papalla juice and offers one for Isabella as well, before telling Clara about an imaginary friend of her own, a Tarcassian razor beast.
The drink is a small detail in one of the series' few stories told largely from a child's point of view.