Manhole covers in Sweden are marked to show what they are covering. A for avlopp (waste), D for dagvatten (storm drain) and K for kombi (combined waste and storm drain). Children joke that standing on an A-drain will give you all the bad things mentioned in the film (AIDS, etc.) while standing on a K-drain will give you love (kärlek).
The English subtitles make this scene a bit confusing; they're actually practicing French pronunciation.
