The other day while I was at gaming, a few friends mentioned Guardians of the Galaxy and how amazingly great it was. I've yet to see it, money constraints and all that. So I commented to them about that.
And they seemed to have ignored it, or figured what they were sharing wasn't all that important. Except it put elements into my head of 'OH, look for that... And hmm, wonder what that means?'
When I saw both Thor 2 and Captain America 2, I made sure to keep from talking or mentioning much of anything beyond 'HOLY CRAP... IT WAS AWESOME!!' to them. Well, and laughing at someones pointed comment about 'Better put on my pants.'
But that was subtle and not something others would be looking forward to in a movie.
I remember a few years ago when I saw.. I think it was Harry Potter 6. 5 or 6, I know that much. And I jokingly put up a status of 'Holy crap!! When ____ and ____ happened? Didn't see it coming. And I loved when ____ happened. So cool.'
The difference? I could have been talking about a million scenes in the movie. Nothing to say what I was actually mentioning.
Another time, after having seen The Expendables, I commented on what I loved. 'Explosions, fights, loud guns, sexy guys, burning rivers of fire, and explosions. Did I mention explosions?'
Ok, I guess that time I gave away the whole movie, but at the same time you were expecting those things anyway, so did I actually give you any spoilers?
When someone says 'I haven't seen that yet' the polite thing to do, is STFU, or at the very least walk away so they can't hear you. Hard enough to avoid learning of things you haven't seen, without friends talking.