How do I do it?

So, my oldest son, Dawson, is almost 9 years old, and I no longer can avoid telling that the way babies are made, is simply by magic. My fear still stands that some punk kid at his school is going to tell him about the birds and the bees (why in the world is it called that?). He is now in third grade, and has kids starting to say dirty things to him, and use disgusting words, so I am just waiting for the big S word to come up, and he ask me what it means. He thinks it simply means whether you are a boy or a girl. How long can I keep him in the dark, or do we need to have the talk now? Give me some ideas on how to explain it to him, without myself turning bright red? I still remember the day my mother spilled the beans. I did not want to know! She took me to McDonald's, and bought me a cheeseburger, and we sat down. I was nine years old, and completely mortified. As she was explaining it, how a woman becomes a woman, and gets "fertilized" I could no longer eat my cheeseburger. As I sat there staring at the lonely cheeseburger, with only a few bites taken out of it, I wanted to throw up what I had already ingested, and was begging for her to be done! I don't want my son to feel that, and I think where he is at now, he won't yet, at least I like to believe that. I feel like I have some magic capability to keep my children interested in being with me, and will never ever steer away from me! HA! What a funny thing that is isn't it? He has for some reason stopped asking me how babies are made, and it is making me wonder if he has figured it out, or he just got sick of hearing "It's magic!" Any help?