Chewing gum
In his memoirs, Lee Kuan Yew said that in 1983, when he was Prime Minister of Singapore, a proposal for the ban was brought to him by Teh Cheang Wan, then Minister for National Development. Chewing gum was causing maintenance problems in high-rise public-housing apartments, with vandals disposing of spent gum in mailboxes, inside keyholes, and on lift buttons. Chewing gum left on the ground, stairways, and pavements in public areas increased the cost of cleaning and damaged cleaning equipment. Gum stuck on the seats of public buses was also considered a problem. However, Lee thought that a ban would be "too drastic".