So my sister usually puts on some TV shows as background noise when she's doing other stuff in the same room, and one particular show she tends to put on it one that I watch ahead of time through... other means. Occasionally I'll make some kind of noise at a line of dialogue, which makes her curious. When she'd ask why I made the noise I would just say that it's a spoiler. She would ask me about it but I would keep my mouth shut since I generally don't like spoiling movies and shows and such. This would usually lead to her insisting on me telling her, but I would keep refusing. This mostly ends in an argument.

Tl;dr, should I just tell people spoilers when they ask for them?