So, I know this funny little trick where you can verbalize a desire and seek explicit permission to act it out while taking care to make sure nothing about the situation seems especially likely to make the other party feel coerced or intimidated into giving an answer out of synch with their preferences. It basically involves paying attention, modelling the other person as an agent, deciding on that basis whether the request is appropriate (while noting the distinction between "appropriate" and "acceptable to the other person") and then asking politely. You do have to take care not to assume that the answer is or "should be" yes, though -- the difference that makes in your approach usually comes off as a bit creepy.
If it happens that you don't know how to perform all of these magical tricks, using your words is a good first approximation. The likelihood of a good outcome is often improved if you ask e.g. "Can I hug you?" as opposed to just bounding up and hugging the person, and your blameworthiness is significantly lowered.
Note please that physically imposing folks who appear to be men and are not charismatic (like social status, but interpreted on an individual basis - the individual one considers highest-charisma is likely to be thought of as creepy by a...
One of the lessons highlighted in the thread "Less Wrong NYC: Case Study of a Successful Rationalist Chapter" is Gender ratio matters.
There have recently been a number of articles addressing one social skills issue that might be affecting this, from the perspective of a geeky/sciencefiction community with similar attributes to LessWrong, and I want to link to these, not just so the people potentially causing problems get to read them, but also so everyone else knows the resource is there and has a name for the problem, which may facilitate wider discussion and make it easier for others to know when to point towards the resources those who would benefit by them.
However before I do, in the light of RedRobot's comment in the "Of Gender and Rationality" thread, I'd like to echo a sentiment from one of the articles, that people exhibiting this behaviour may be of any gender and may victimise upon any gender. And so, while it may be correlated with a particular gender, it is the behaviour that should be focused upon, and turning this thread into bashing of one gender (or defensiveness against perceived bashing) would be unhelpful.
Ok, disclaimers out of the way, here are the links:
Some of those raise deeper issues about rape culture and audience as enabler, but the TLDR summary is:
EDITED TO ADD:
Despite the way some of the links are framed as being addressed to creepers, this post is aimed at least as much at the community as a whole, intended to trigger a discussion on how the community should best go about handling such a problem once identified, with the TLDR being "set of restraints to place on someone who is burning the commons", rather that a complete description that guarantees that anyone who doesn't meet it isn't creepy. (Thank you to jsteinhardt for clearly verbalising the misinterpretation - for discussion see his reply to this post)