I have a guy whom I met at workplace was once jailed before. I ask him what offense he commit he told me he farted on the MRT train and get charged in court. My answer "I dun believe u" but that's what many of his mates in the jail said to him when he told them the same thing too.
Okay one morning this guy took a MRT train, it was crowded then, and he was standing next to this woman. Allright he give a, erm ye noe and he foolishly give a smile! The woman called down the MRT people and the police was called in, kena sentenced for 3 months in jail! Hahaha

Another of my friend who was with me was not surprised, he said this is the result of over-pro-woman lasws of singapore. I told this inncident to my friends in the SCDF, and one of them happen to have a friend who is too, jailed for fa*ting on the train!
Ask him how he felt about this incident, "Sway loh" Hahahahaahha

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From my opinion I think he was jailed for insulting the modesty of the woman rather than his action. He smiled maybe that's why they believe his action was intended in the first place. I don't know cos he did not tell me what offense he was charged under and he was too jailed before for 2 other offences long before.