You're probably wondering what to expect...
I was teaching electronics and working on a new FDDI network installation in Thailand last year. The company had me staying what can only be classified as a mansion, next door to the ex-Prime Minister's estate. They had a young lady who did the cleaning and such, but I did my own cooking. I needed some food, so I hopped out to catch a cab to one of the farang (foreigner) catering stores. They had mostly British foodstocks, but some items looked familiar.
I am a coffee-holic. I bought my coffee, some non-dairy creamer, and started looking for the sugar. Try as I might, I could not locate the sugar, since they seemed to stock the grocery in a random fashion so they can laugh at us. I happened upon a stack of what appeared to be sugar... it certainly looked like it, it was even in a bag that was amazingly similar to the brand I always bought back in the 'states. Unfortunately, it was in Thai, and I read Thai as well as backwards phonetic binary. So, I assumed it was sugar and snagged 2 bags.
I should've thought twice when I started getting weird looks from the cashier. Since she only knew "Thank you" in english, I couldn't ask. So I caught a taxi back to Pholyothin Road and put things away.
Next morning I forgot about my doubts. I popped some grounds into the french press coffeemaker, boiled some agua and got the cup ready. I poured the steaming bitter coffee into my cup, tossed in a slattering of creamer, then heaped in five teaspoons of sugar.
Well, it turns out it was not sugar, but crystallized MSG. Yup, monosodium glutamate, the stuff they used to put in chinese food. Let me tell you, it was the most foul taste I had ever experienced. I've had a salted 7-Up before, and that was bad, but this was unbearable. I spewed what I didn't swallow all over the kitchen floor. What I swallowed followed soon thereafter, along with the bacon and eggs I had eaten earlier. I rinsed my mouth out over and over, but it seemed to have attached itself to my salivary glands. As my mouth watered I'd start gagging anew. Even to this day my stomache does a flip or two when I remember it.
Moral of the story: They were right when they said never assume. If you don't know what it is, ask. This new philosophy helped me avoid several other things that would have made this list, like ground mealworm paste, dog kabobs and BBQ'd praying mantis on a stick.