"Persassy" is a word created by the Percy Jackson fandom. It expresses how much sass the protagonist, Percy Jackson, has by literally including it in his name. It's used to describe how sassy and sarcastic one can be.
Percy: The ocean is too wet.
Whale: ...dude, are you high or something?
Percy: Nope, I'm just Persassy
Used as an insult. If you say someone is ‘spare parts’ then you’re calling them useless, or they’re so poor at what they are doing that they might as well be doing nothing.
In a co-op video game, if there’s someone in your party that ends up doing jack shit for the team, then you’d say they are “spare parts.”
Player 1: Dude, player 3 got no absolutely no kills the entire round.
Player 2: I know, right? He just sat on his ass the whole game!
Player 1: Yup—he’s spare parts.