Link: https://en.wikipedia.org/wiki/Chewing_gum_sales_ban_in_Singapore

The sale of chewing gum in Singapore has been illegal since 1992. Some motivations for the ban included stopping the placement of used chewing gum in inappropriate and costly places, such as the sensors of subway doors, inside lock cylinders, and on elevator buttons. Since 2004, an exception has existed for therapeutic, dental, and nicotine chewing gum, which can be bought from a doctor or registered pharmacist. It is not illegal to chew gum in Singapore, but it is against the law to import it and sell it, apart from the aforementioned exceptions. According to a BBC News article, it is legal for a traveler to bring in a small amount of chewing gum for personal use, and there is a fine for spitting the gum out in an inappropriate place.