Karen finds some examples of lessons from actual abstinence-only sex ed lectures. They're eye-opening.
I expected to hear misrepresentations of data on condom effectiveness, and claims that abortion makes you crazy. I did not expect to hear stories about how making suggestions to boys makes girls unattractive, or an explanation of how boys carry their books so as not to look gay. I think one of the less discussed problems with these programs is the stuff that's not directly related to sex, but rather to gender roles and aptitudes. Girls can't analyze things without their emotions getting in the way? It's boys who seek accomplishment and adulation, while girls really only care about relationships? What does that even have to do with abstinence?
The Choosing the Best course series, from which the knight story was pulled, claims to have already been taught to over 3 million kids. Speaking of, I looked around a bit for some confirmation that these came from actual curricula as opposed to some puritanical teacher speaking off the cuff, and I found the knight story referenced both in the company website's list of revisions, and also in the Waxman Report on abstinence education. The Waxman Report is very skimmable and similarly damning. I recommend a read.