since 1992,Of all the things, chewing gum is illegal in Singapore. It seems like a basic right to make such a non-consequential decision, whether or not to chew gum. But the city state has made this decision for everyone there. In America, the ACLU would have filed a lawsuit so fast against the ban that by the time I had my gum wrapper off, the law would be repealed.

Nonetheless, Singapore has had this anti-gum-chewing law on the books since 1992 and it is enforced. In fact, the ban includes imports or sales of chewing gum. In addition, police spies roam the crowd of 4 million in the city to find offenders who chew gum or litter. Residents and citizens say that it is just something that they’re use to and if you’re doing the right thing there’s no problem. Others say, especially cited tourists, “if you’re going to ban chewing gum due to litter, why not ban smoking too or eating fast food (which both create litter)?” 
Singapore decided to ban chewing gum in order to keep the city clean. In fact, it has been deemed the cleanest city in the world. Before 1992, some people were disposing of the chewed gum incorrectly causing gum to turn up in “odd places” like under tables (never heard of that odd receptacle).
If you’re traveling to Singapore make sure that you clear your bags and pockets of chewing gum. Bringing even small quantities of chewing gum is prohibited.
According to Wisegeek, the penalty for chewing gum in Singapore is similar to littering laws: “The littering law requires a fine of $500 to $1,000 US Dollars (USD) for first time offenders. Repeat offenders may be fined up to $2,000 USD and assigned a Corrective Work Order (CWO).
When serving a CWO for violating littering laws, offenders are made to clean public spaces, often while wearing a bright colored jacket. The media may also be invited to cover the event, increasing the severity of the penalty though additional public shame.”

In Singapore, the ban is on the sales of chewing gums, not on the consumption. This means that you can bring in small amount of chewing gums for your own consumption, but not to sell it.

You can also chew the gums right in front of the police, and they will not arrest you…because the law is clear about the ban on sales of chewing gum, and no one will be prosecuted for chewing gums.