People who grew up eating natto (fermented soybeans) love it, but to everyone else it's an offense to all five senses. The smell is like old gym socks. The sight of the sticky, spiderwebby strands hanging from lips or chopsticks is revolting. The taste is like, um, what old gym socks must taste like. And the texture is the worst combination of sticky and slimy. (That was only four senses, wasn't it? Fine, I'll grant that hearing isn't traumatized.)
After living in Japan for almost nine years, I decided to grow up and acquire a taste for the stuff by sheer force of willpower. It's said to be very healthy and I enjoy other fermented foods like yogurt and cheese. Last week I ate some with rice and nori (dry seaweed). This evening I ate two servings. I was able to swallow it without gagging or needing to wash it down right away. I don't plan to start ordering it in restaurants or anything, but I'm happy to say that pretty soon when I'm asked the inevitable "You're a foreigner so you can't eat natto, can you?" I'll be able to answer, "Yes, as a matter of fact I can."
[Photo Credit: ...natto... by roboppy]