Virgin Sacrifice

Roosterbooster said:
Also the whole virgin sacrifice thing made no sense to me, I mean if only a virgin can be sacrificed surely there are <ahem> ways around that if you're the girl in question? But then it is a Disney film.

To be cynical, you'll notice that Valerian set out to be innoculated against her fatal condition soon after it was revealed to the world. To be humorous, there's always the SCA song "Do Virgins Taste Better?", which would actually seem to have some root stock in common with Dragonslayer.

http://www.thebards.net/music/lyrics/Do_Virgins_Taste_Better.shtml

Seriously, however, the definition of "virgin" is not always "someone who has never had sex". It can also include "young women who are not married" or even "women who have not yet married or borne children". Thus, just because you have had injective innoculation, does not mean you are safe from the dragon... just that you've had some fun before you went.