Montezuma's revenge
slang Diarrhea, especially that which is contracted from food poisoning. Usually refers to tourists traveling in Mexico (Montezuma II was the emperor of Mexico in the beginning of the 1500s) who lack immunity to bacteria that can be transferred via food and local drinking water. The best way to avoid Montezuma's revenge is to drink bottled water.
Montezuma’s revenge
(mɑntəˈzuməz rɪˈvɛndʒ) n. diarrhea; tourist diarrhea. (Refers to tourists in Mexico.) I had a little touch of Montezuma’s revenge the second day, but other than that we had a wonderful time.
Montezuma's revenge
Traveler’s diarrhea, contracted by travelers in Mexico but elsewhere as well. The expression alludes to Montezuma, the last Aztec emperor. and dates from the mid-1900s. Tennessee Williams used it in The Night of the Iguana, as have many other writers. Another name for the condition is Aztec two-step, but that has not become widespread.