Because if there's one thing that can help prevent pregnancy, it's definitely novelty underwear. Suck it, condoms!
A company called WWYMD (what would your mother do? Not buy me novelty underwear, that's for sure!) is selling women's underoos with messages like "dream on", "zip it" and "not tonight" printed on them to discourage ladies from having sexes with the dudes (or the other way around). I question how effective they'll actually be though, which is why I just started my own company and had some printed that read, "PUT YOUR PENIS IN HERE AND A BABY WILL FALL OUT" across the waistband. Unfortunately I'm a terrible planner and everything but "PUT YOUR PENIS IN HERE" is on the back.
Thanks to Drew, who's comfortable enough in his manliness to send tips about women's panties.