USE A RUBBER There are somethings that a photo of a teenage pair should not have. A kid is one of them. Use a rubber, erase it out of the frame. Use a rubber, ensure that a kid does not enter your life before you are ready.
We made this for an Ad Club activity in college for which the brief was to make a campaign to "encourage sexualy active teens to use protection".
Personaly, I believe that abstinance is the only 100% safe solution.