The Transylvanian Trots, the Hershey Squirts, Delhi Belly, the Orient Express, the Evacuation of Paris: they all mean diarrhea. Stay close to a bathroom, drink plenty of clean, bottled, or boiled water with a little salt, and/or flat soda (not coffee), and be careful not to get dehydrated. When in doubt as to the severity of an attack, there is no doubt about what to do: swallow your pride and see a doctor. Greasy food, particularly that processed mystery meat cooked on vertical spits, is a prime suspect in this problem, as are salads, and drinks with ice if the local water is suspect. Plain, preferably live, yoghurt can be very soothing to the system if this occurs. If you are going out in the wilderness, especially in Greece, Turkey, Morocco, or Russia, some packets of rehydration salts would be a smart thing to carry, just in case.