in my opinion, it depens on how old your characters are, I would say: not younger then 15/16. those girls or boys are pretty concious(did i spelled that correct?) of thereselfs, therefor I would see no harm in that. however, little girls of seven year old would be sick in my opinion.

crossing taboo's works in two ways, One may speak about something that another person don't want you to speak about, but when you do, you don't have to throw it in his/her face, the right to NOT hear the things you want to hear is just as important as the right to say want you want to say.

(damn I've got to work on my english!)