@Dunecate - How exactly do you dismiss the distinction that oral sex is not sex as being just the result of some universal desire for duplicity on the part of "youngsters", and then declare (without apparent justification) that the definition of "sex" is actually the broadest possible interpretation?
I mean, arguably, its just an issue of semantics (there are clearly different acts, and which ones can be described by the word 'sex' is a matter of arbitrary choice) and insofar as that is concerned, words should be as reasonably precise as possible - i.e., that "sex" should be limited to PIV (or in the case of homosexuals, equivalent) intercourse. For heterosexuals, at least, it seems right to limit it to the activities that barring birth control or infertility, could impregnate a woman.
This is more or less the case in practice, as well. If a woman blows you, it would be odd to say "I had sex with her". That statement implies intercourse.