For instance, I did have a pretty comprehensive sex ed in school, but there's stuff in life that you just don't know about til you get there...like, who sleeps in the wet spot? Or:
How do you shave/trim pubic hair?
How do you not get a maxipad stuck to your hair/leg?
What's the warning signs that your SO is actually a giant arse?
Kind of along the lines of "What I wish I knew at 16" if you will.