That thing men do when they insist on holding the door open for you, even when you both got there at the exact same time, and the door is opening towards you, so it would be much easier for you to hold it for them to go through.
Firstly, it's annoying, in a basic "what, my spindly lady arms will snap if I open a door for myself?" kind of way.
Secondly, it's annoying on a more complex, "I am being chivalrous and demand that you accept my chivalry, or I will castigate you as ungrateful, unfeminine, and out to symbolically castrate me" level.
Thirdly, it's actually kind of invasive: unless it's a very wide doorway, you're basically forced to slide your body incredibly close to his, hoping that he won't take advantage of the configuration of your two corporeal forms to grope you or grapple you or press his wang into your hip on your way past.
It's one of those moments where you see so clearly that this system of social relations that makes life so difficult for women is not perpetrated exclusively by moustache-twirling patriarchal villains, but, sometimes, by individual men who think they're doing a nice thing. Who can't step out of their own experience for thirty seconds to understand what an interaction looks like from someone else's point of view. Who don't deal with the daily encounter with Schrödinger’s Rapist, and don't realise that women do.
This is one of bell hooks' many vital concepts: that those on the margins must understand the rules of those in the centre, but those in the centre can live in total ignorance of what life is like on the margins. I understand that every guy who's ever held a door for me is not trying to piss me off or violate my personal space, either to enjoy the exercise of his tiny little power, or to remind me of my subordinate place in The Grand Pecking Order Of Oppression. But he doesn't know that this is exactly the impact it has on me.