1/ A genuine expression of surprise when you meet someone you know in an unexpected place
2/ A sarcastic greeting when you meet up with someone at a previously agreed destination.
This phrase was brought about in the time of debates over "Universal Health Care" and the way people behaved in the face of differing opinions.
It means to disagree vehemently, to aggressively object,
When people aren't in a relationship but are willing to engage in sexual activity with each other but also won't be bad if the other person has sexual activity that isn't them. Basically a pass to cheat.