When I say "weird", I really mean anything that you may think of as stupid. The whole point is that we can't filter out every idea and prove it's a bad one, but if we don't dismiss them they can at least rise through to the top through natural selection via survival of the fittest.
About the twin getting his brother's arm, that was actually an April fool's story that bme ran: http://www.bme.com/news/people/A10101/addsub/fools.html
Also, I don't "discourage weird behavior". I do discourage "weird behavior who relies on my acceptance of the terms", and that's what bugs me about amichail constant polls and 'ASK YC' posts.
To make an analogy, I don't mind reading about people who are into body modification, even to the point of sewing off their twin brother's arm, and reattaching to their own body (http://www.bme.com/news/people/A10101/addsub/). That is weird as fuck, but their experimentation does not rely on me participating in any way. You can bet that I would mind a lot if said twins start going around telling people how cool it is to have your brother's arm attached to your arm pit and that is "rather unfortunate" that nobody else listens to them.