I don’t think it’s a weakness to not always stand up for it… to always, constantly be on edge is exhausting sometimes, and quite honestly no one likes being the “What did you just say!” person all the time. 

  I probably do it more frequently than a lot of people and it’s just like this blah combination of feeling obligated to but not liking it, while simultaneously everyone perceives you to be the kill-joy who gets their kicks out of killing joy.   For me though I’ve just adopted a steamroller mentality.   If you don’t agree with me, you can get out of my way.   You can stop being my friend.   You can be embarrassed and angry when I ask you why the fuck you think a rape/racist/whatever joke is appropriate to share.    If one of us has to feel awkward in a group of friends, it’s going to be you.

At some point you just need to not care what those people think of you, because once you get over pretending that their opinions about you are valid, you’ll feel a lot better about yourself.   I’d rather try (and sometimes fail, but try) to stick up for the people who are being pushed down, than try (and usually fail) to suck up to the people who are pushing.

And sometimes if you still feel like dealing with them, humor is the best strategy.   Adopting it in your arguments throws people off kilter if they expect you to be a total killjoy, and also helps to make clear that you’re not (or at least, you’re pretending to not :P) be bothered by their insults.

Ex:

“Gawd Marcia Brady, why are you so bitter?  It’s just a movie.  Just enjoy things for once.”

-amused smile- “Who said I didn’t like it?  I loved the part with x.   Am I wrong to assume we’re all mature enough to have interesting and stimulating conversations critiquing the media we watch?   Like let’s be real, we’re not 8 years old.   We can have a conversation about issues with Batman without crying about the movie being ‘totally ruined’ for us.   …Can’t we?”  WHOA TABLES TURNED.  Idk.  That won’t always work.   But IF you continue to feel bad about not speaking up, then I’d recommend speaking up, and just adopting a strategy that works for you personally.