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.
A phenomenon in film/television series, most notably streaming series, where the main premise is drawn out to such a point that it takes an entire season or more to get the parts of the series the audience is actually interested in seeing.
For example, if a series is titled "Surf Dracula," a majority of viewers would tune in expecting to see Dracula surfing by the first or second episode. However, the entire first season would instead be tedious padding and backstory before finally ending with Dracula surfing in the last five minutes of the season finale.
I watched "Smallville" on Netflix the other day. Dude, it was ten seasons of filler before he finally flew! Major Surf Dracula Syndrome!