This is from Trivia Today and I thought it was very interesting:
Question: In which country is it illegal to sell or import chewing gum?
Answer: There is a ban on selling or importing chewing gum into Singapore which is strictly enforced. The sale of gum was banned in 1992 after gum was used to shut down the SMRT, the country's public transportation system, after it was stuck on the sensor doors and brought the system to a halt. The punishment for smuggling gum into the country is a year in jail and a $5,500 fine. Since 2004, only chewing gum of therapeutic value is allowed into Singapore under the "Regulation of Imports and Exports (Chewing Gum) Regulations." Gum can be bought from a doctor, but must be prescribed.