In Singapore you can only buy nicotine gum and other kinds of gums that benefit your health, such as sugarless. The amounts are limited and pharmacies have to record each sale in a logbook like this one.
This actually represents a softening of a previous ban on gum, which the government adopted after people started messing up the city's nice new subway with gooey blobs. The new rules were brought about by the US Singapore free trade agreement of 2004. Wrigley's is said to have lobbied hard during the negotiations.