There's a book with a nice quote - I think it is Forest Morgan's "Living the Martial Way", but it may not be.
The author talks about going into bars and getting into fights all the time. Then realises that he goes in and sizes up all those present subconsciously, thinking "I could take him, him, ....".
Things get more peaceful when he goes in to bars with the attitude "everyone in here is safer because I am here..."
One thing I can do pretty well is walk past the groups of teenagers that hang around street corners where I live, without them calling after me or actually reacting in any particular way at all.
I think what usually happens is adults (especially women I'd imagine) feel threatened by a group like that, and the kids in turn, being teenage kids, already feel insecure and selfconscious and sense very easily that they are being judged. So they react, you could say in self defense.
So I think things like "what a nice evening to be with friends" or something like that, sort of get into the same frame of mind as the kids, and I walk right by them and they just go on with whatever they are doing.