I've been given the intimidation routine ("You know this means I'm going to touch your private areas," and "Do I need to call a supervisor?") and the downplay routine ("it'll only take 3 seconds and it's completely safe"). It's always in that order. It's always the same; send the bully then send the supervisor. It take 5 minutes to go through that. I've taken to simply standing in silence with my arms outstretched and legs apart.
Everywhere else is easier.
"Call someone, because as is my right I would like to request a private screening room, please."
Flying out of SFO (where they have MMW machines, at least in the terminals I use), there's another person opting out about half the time. If I get a chance, I'll ask them why. It's almost always a matter of principle, as it is with me.