I suppose there are some things I would have to give serious consideration too before I consumed them, but in general I will eat (and like!) most anything. That being said, the only thing that has made me physically ill after simply placing it in my mouth is natto.
http://en.wikipedia.org/wiki/Natt%C5%8D
Really, just awful stuff and I really enjoy all other forms of Japanese cuisine. I've now tried it three times and my opinion is unchanged. The crazy thing is that this is a very common part of most Japanese diets...for breakfast!