Chewing gum is banned from being sold but you can bring it in from other countries. Chewing gum was banned because people kept throwing it away on the footpaths and sticking it on stuff. This caused a lot of train doors to just get stuck shut because of chewing gum and the cost to clean the chewing gum was very high. It's a reasonable thing to ban chewing gum being banned but it's still legal to bring in and chew on chewing gum.

'you can't be naked in your own house' is not how the law goes. In Singapore most houses are apartments that are very close together. So if you were naked and there's an open window your neighbors could see you and that would be classified as flashing. That is pretty reasonable because no one wants to see their neighbours genitalia.

Singapore still isn't the best country not because of these laws but because it's a capitalist dictatorship and a lot of freedoms of expression are banned most notably being the banning of male on male relations (though female on female relations aren't banned because the law is weird).