Couples like this are exhibitionists, but when another commuter so much as looks their way, they will feel uncomfortable. My female colleague who is in her 40s, just gazed in the direction of a couple who were kissing in the train, and the Ah Lian GF asked her: "Why auntie? You never have sex before, is it?" My colleague told her to go fu-k herself and her BF somewhere else. LOL!