Talking about one’s sexual history is an important part of new partners’ communication with each other. After all, they say that you’re not only having sex with this new person, but with everyone he or she has had sex with too (sort of a “six degrees of Kevin Bacon” game with a sexual twist). But how do you know your partner is being truthful when informing you that he or she has had three, thirteen, thirty, or three hundred past partners? People certainly have reasons for being less than honest (like you don’t want others to judge you based on your busy, or not so busy, bedroom), so when they self-report about their sexual behaviors, how do we know they are not lying? People often fudge their responses about things like how much they recycle and go to the gym because those lies make them look better, and researchers need ways to get participants to tell the truth when reporting about all sorts of “socially desirable” behaviors.