What is your least favorite food?

Very possibly escolar, a fish which shows up in sushi assortments from time to time, often mislabeled as a different fish.

Escolar flesh contains indigestible wax esters that cause oily diarrhea. Curiously, "escolar" is almost an anagram of "Olestra", the indigestible fat substitute that causes the same problem.

Escolar cannot be legally sold as food in some countries, including Japan. If it's in your sushi, don't go back to that sushi place.