slang Diarrhea, especially that which is contracted by tourists who lack immunity to bacteria that can be transferred via food and local drinking water. "Basra" is a city in Iraq. The best way to avoid Basra belly is to drink bottled water.
Basra belly
(ˈbɑsrə ˈbɛli)
n. diarrhea; a case of diarrhea. The Basra belly hit me while I was on the bus.