depends on how ugly the kissers involved are

That depends on where in the world you are. In America, kissing in public is not illegal.

As far as I know, no US state has it outlawed. But, I found this on the net in a CNN article; Kissing ban considered for Moscow metro Friday, November 7, 2003 Posted: 4:46 PM EST (2146 GMT) MOSCOW, Russia (Reuters) -- Couples caught kissing on Moscow's underground rail system could be fined under new regulations being considered by city authorities while those going too far could face jail, a newspaper's Web site said on Friday. The kissing ban could even extend to a husband embracing his wife, Stolichnaya Vechernyaya Gazeta said on its Web site. The newspaper, quoting unnamed sources, said the city authorities were thinking of introducing the ban to raise levels of public morality. "From the New Year citizens kissing and embracing publicly will be fined," it said. "Particularly blatant cases could even lead to a spell of temporary detention in jail," it added. It quoted a city education official, Tatyana Maksimova, as saying metro travellers were indulging in increasingly lax behavior including drinking alcohol from bottles and cans. "Our children are getting love lessons all day long from what they see around them," Maksimova said. Moscow police would not comment on the report. -end. We are a ridiculous species.

Depends on the place where you will do IT. Well, check out this youtube video. http://www.youtube.com/watch?v=X7PH7qIfNC4 They were caught after kissing for a long period of time inside a crowded mall! lol