Memberberries are sentient fruit first used by Mr. Mackey in his office. Later, Stephen Stotch shows them to Randy Marsh. Their main function is to remember pop culture icons, bringing about nostalgic feelings for the supposed good times of the past.
However, they also make homophobic and racist comments, such as remembering when marriage was only between a man and a woman, when there weren't so many Mexicans, and Ronald Reagan.
In "Fort Collins" they seem to be aware of their surroundings as they were seeing a normal memberberry experimented on.
They are also seemingly indestructible as one was seen burned by a torch, acid, and electrified with little to no effects. However, they can be squished.
They appear as normal looking grapes with faces on each piece and speak in a very high-pitched voice.
The memberberries are the physical manifestation of the idiom "sour grapes", used to refer to a negative attitude to something because they cannot have it themselves.
- "Member Berries" - Seen being eaten by Randy Marsh and Mr Mackey.
- "Skank Hunt" - Mr. Mackey is seen enjoying them, until Scott Malkinson frantically enters Mackey's office.
- "The Damned" – Seen as an ingredient in a pie as well as whole fruits.
- "Wieners Out" – Overheard in a man's shirt pocket, and the man squishes them.
- "Douche and a Danish" - Seen blamed for society's want for Mr. Garrison to become president.
- "Fort Collins" - Seen getting Caitlyn Jenner to eat a Member berry: a gang of memberberries escapes from Randy's house and takes a hostage memberberry with them. They kill their hostage by pushing him off the shelf of a bar into Caitlyn Jenner's martini.