What it means
To hate-watch is to keep watching a show or film you actually can't stand, purely for the fun of mocking how bad it is. You're not enjoying it, you're enjoying being annoyed by it, live-texting the worst bits to your friends. The worse it gets, the more committed you are to seeing it through.
Usage examples
"We hate-watch that reality show every week just to roast the contestants."
"The series got so bad it crossed over into pure hate-watch territory."
"We said we'd put one episode on as a joke and now we're six deep in a full hate-watch spiral."
"I'm not even rooting for anyone anymore, I'm just hate-watching to see what fresh nonsense they pull next."
Where it comes from
A straightforward mash-up of hate and watch from the streaming era, when finishing a terrible series became its own ironic hobby.
This expression also appears in