Have you ever had anyone make an inappropriate but friendly pass at you?
My technique is to just put a hand to face and say NO. Like you'd do to a naughty dog. Rap on the nose with a newspaper, basically. And then just carry on with being friendly and whatever conversation you have going on.
This is certainly guy privilege, but ladies always back off. Always. And usually apologize and say hahaha, I'm dronkity, sorry, and then we can laugh and get on with whatever stuff is going on and just be friendly. Guys? I dunno, they might not. Guys can be tremendous assholes that way, I think. We're trained to think no means yes, it's fucked up.