To try and give youngsters a grounding in the Birds and Bees. Tried to show the responsibility that parent hood brings, but not in such a way as to put you off for life, just to dissuade from unprotected sex. Also teaches basics about STDs.
Normally a source of great amusment to teenagers accross the planet. Maybe if the didn't find it so funny we wouldn't have such a high teen-pregnancy rate. It could even help curb the population explosion the world has experienced over the last 100 years.