Creepy behaviour is behaviour that tends to make others feel unsafe or uncomfortable.

It would be really good to have a definition that had some shreds of objectivity to it. As it stands your definition simply assigns to one person the responsibility for another person's feelings. This is infantilizing to the 'victim' and places the 'perpetrator' at the mercy of the "victim's" subjectivity.

The alleged safeguard that a significant fraction must agree the behavior is creepy is rarely applied in practice. "If you made her feel creeped out, man, that's creepy".

In practice this definition of creepiness is almost solely used against men. I had a female colleague (many, actually over the years) who wore inappropriately 'hot' outfits at work and behaved in overtly sexual ways that left me feeling uncomfortable. One cannot complain about this because it is "slut shaming".

I notice a disturbing trend for rationality orientated groups to be invaded by people who like to impose long lists of rules about acceptable behavior and speech, generally with a feminist flavor. These people generally have made little to no contribution to the groups in question. I see here for example OP's first post here was all of three months ago. The open source and atheism communities have seen similar phenomena.

We need to expose these people and their ideas to full rational scrutiny. I have read a lot of feminism literature and I believe that the field could benefit significantly from an infusion of LW style rationality.

Finally can I point out a clear source of irrational thinking that tends to surface in these discussions: the "protective instinct" towards women. For reasons that don't particularly matter in this context, when we see women (or children) at the risk of harm, powerful emotions arise. Thus, if you want a massacre to sound as bad as possible you say "100 people were killed including 50 women and children." In movies, it is almost always unacceptable for a sympathetic female character to be killed (read any guide to writing move scripts).