13 year old son already talking about...?

Help, I am not by any means in denial about the knowledge that my son has of . I have talked to him & expressed that he should wait til he is 16 before he even entertains the thought of a g/f, he said "mom by the time I'm 16 I'm going to be behind a dumpster~ " Joking or not I can only imagine the kind of girl he'll have behind the dumpster! How do you teach him to respect himself more than that? I've shown him the greatness that comes with ... STD's, AIDS, & but none of that scares him.