Worst diarrhoea - Suffered stomach flu or "Influenza" one day before my trip to Japan with my wife in year 2002. Went to see doctor and got a jab and go home to rest till night flight. Dreaded sightseeing commenced immediately upon reaching Osaka the next morning. The 2nd day when the rest of the tour group went to Universal Studio, I was on dip in a Osaka hospital for half a day, with my wife accompanying beside me. The rest of the trip, I was basically searching / squatting / shitting in every attraction I went; Tyoko, Kyoto, Nara, you named it, chances are I went there to 5hit before.
Naturally the whole trip was a disappointed and I still owed my wife another trip to Japan.