He looks mostly like the normal Patrick, but is tiny, wears completely green shorts with no purple flower pattern, and does not have any freckles.
He also babbles in unintelligible gibberish rather than real speech.
Role in episode
When SpongeBob and Patrick are sad that they have to leave each other, they decide to cut out parts of their body to make mini versions of themselves, and SpongeBob gets the Patrick mini. While he is with SpongeBob, he is initially treated with kindness by the latter but repeatedly gets tortured soon after. He and Mini SpongeBob break free and decide to torture SpongeBob and Patrick so they can get a taste of their own medicine.
The Patrick and SpongeBob minis try to have a good living in SpongeBob's house, but they are too small, so the big SpongeBob and Patrick give the Patrick and SpongeBob minis their own houses. Mini Patrick gets a small rock that is identical to the big Patrick's rock.
Afterward, they feel something is missing and soon Squidward finds himself in the sand while the Patrick and SpongeBob minis are playing. He is annoyed at the pair abducting him and by how they proceeded to annoy him like their creators, though felt bad after he is annoyed by their antics and they hug his nose as an apology, to his dismay.