a good way to break the ice is to see why they are bored, if your waiting on line or if they are just sitting down at club.........then you can say why arent you dancing, or you dont like this song much do you, if they are pissed then you can say something laong the lines of oh, i see it must be your birthday
either way relax and if they just push you off, well.... you didnt know them anyway, just dont be an asshole on purpose.
remember, the world is cruel, everyone is at least a little lonely but probably too much of a coward to talk to strangers and make new friends....what can i say, im jaded