My take on the situation isn't so much that the "virginity pledgers" don't know their safe-sex options but that because they've taken a public oath to not have sex until marriage, they're much more likely to be unprepared and secretive about the whole thing. When you've publicly sworn not to have sex, and the odds are fairly good that your partner has done the same thing; it's probably going to be a spontaneous act that you're going to want to keep hush-hush. Thus, condom purchases before the fact aren't very likely.

That's not to say that I think abstinence only education works. My point is that although I was taught about safe-sex in school, I feel that I would have at least learned the basics about STDs and how to prevent them from the popular media and the problem stems from the fact that stigmatizing sex as shameful creates a climate where youths behave secretively and ultimately, unsafely. Now, I'm fairly well read and I've watched more than my share of movies and television so I know that those messages are brought up in magazines, in Public Service Announcements, and in the infamous "Very Special Episodes" of TV shows, etc. So unless a teenager has been completely cut off from pop culture, they've been exposed to the concept of STDs and their prevention.