The party hands are minor characters on Edgy Oobi.
They are Oobi's party guests. The green- and blue-eyed guests are the ones responsible for introducing Oobi to their blue sports drink, which they call lean, and making him experience its psychedelic effects.
They appear in "Oobi Tries Lean" dancing to trap music in Oobi's kitchen. Grampu is trying to sleep in his bedroom when he hears them and goes downstairs. He tells the guests to be quiet and marches back upstairs, where he fluffs his pillow and goes to sleep after saying "God, I miss Brendan Fraser."
Oobi's party guests are shown mixing "lean" (which is obviously just a blue sports drink) in a glass. Oobi asks them what they're doing and they claim they're making purple drank. Oobi says it sounds great, so he steals their glass and pours it all over himself.
Like most of the other characters, they are talking hands without clothes or accessories. They have various different googly eye colors: red, blue, green, and yellow.