Even when they're not hitting on you, they still do the 'flexing' version.

Standing too close, taking up too much space etc. Just to get a reaction.

It never stops.

I was at an airport last summer; hardly anyone at the gate. A guy young enough to be my son was talking on the phone, came right over and stood in front of me.

So close that I would normally have uncrossed my legs to avoid contact. This time, I didn't and I didn't even make eye contact. Just stared out the window, rooted around in my bag, etc etc. Pretended he was completely invisible.

He got the message after a few minutes.