While this may seem like an odd statement in any other nation, in Singapore people take this extremely seriously. This is mainly because this regulation or ban on non-medical chewing gum is strictly enforced by the governing bodies of Singapore.
All forms of chewing gum except dental or nicotine gums are forbidden within the borders of the nation. You will only be able to purchase gum from a pharmacy with a prescription from a doctor.
All of this was set about as a part of government regulation to ensure the cleanliness of the nation. Interestingly, one of the main motivations that drove this regulation was a finding that chewing gum being thrown in the subway was causing major delays and obstructions to the functioning of the metro operations.
Speaking of the subway, it is also forbidding to eat or drink when using the public transportations around the country, again to maintain the standards of cleanliness that are expected.