In my social group one of the men has a very sexist, puerile and misogynistic sense of humour. I can't be doing with it and try to avoid him but there have been a couple of times I've pulled him up on it, when what he's said has been so offensive I couldn't not say something. It never stops though (yawn), even when nobody laughs or everyone in the group ignores him he still giggles at himself and carries on 
Even though some of the others in the group say to me privately they agree I feel as if it's just me calling him up on it and feel that I'm just going to be seen as a killjoy so I don't do it very often.
Has anyone else managed to get somewhere with a similar situation or is it a lost cause, do you think?