If people stare at my girl I just tend to ignore it... I mean, what else can you do really apart from have a go at them and make YOURSELF come across as a hard on. I'm so not into having to defend your and your girlfriends honour over someone staring at her. You know? If you can just ignore it then it doesn't make any difference who's staring.. And in the end too, they could be staring because they think she lookes like an identical match for their sister, or someone they know, so I feel getting your panties in a knot over a few guys staring at your girl means you should probably look at your anger or insecurity levels... It's something that takes way to much energy to worry about, so don't...

Comments, i'm with someone else who said depends on the comment... Generally if you're their and they make a comment in front of you, it's obvious they are being a smartass and NOT genuinelly trying to pick up your girlfriend, so the best reaction possible is to just be a smartass back and try to, you know, join their humour or something... Getting all hot headed over a little comment is just a waste of time...
I havn't had anyone ever say anything REALLY bad about my girlfriend, but if people whistle or say something like "nice ass" or "nice tits" or whatever like that, I just say "thanks!" or something like that... or "thanks but i'm not gay guys".... They don't expect it and most of the time it gets a laugh.. some people realise that you've just made THEM look stupid and they'd get angry, in which case, DON'T bother turning around and getting angry back, just keep walking and smiling yourself... Who ever made the comment originally set out to disturb your day, and now they're the ones that are angry and disturbed so what more can you ask for...

Unless you've had a REALLLLY shit day and someone commenting on your girl is the perfect excuse to punch the crap out of something! I've had days like that but unfortunatly no guy has been unlucky enough to comment when i'm in that sort of mood.

Final word, ignore it and you'll forget about it 2 seconds later.
Get worked up about it and it'll piss you off for hours, and who could be f'd being pissed off for hours over 1 comment from someone you don't even now.