Vagina Rhymes With China

I was putting the kids to bed last night. William goes in with out a hitch lately. All I do is say, "It is time to go Night, Night." , and he starts sucking his thumb and right in the crib he goes. Abby has been good lately too. I should knock on wood saying this because it seems like when bedtime routines start to go smoothly you can pretty much expect something will change at any moment. Charlie has always been a good sleeper and easy to put to bed, except lately. With all that he has had going on lately I guess I should expect his frustration to come out here and there. Last night after the usual bed time routine, I tucked him in said "Good Night!", got a hug and a kiss and came down stairs. I was quickly called back up. First he wanted a drink, then he wanted to talk. I did both of these things and came back down. He called me again. Now he is usually not like this. I was actually thinking that his voice sounded like Abby's. She is usually the one calling down to me! I went up for the third time, trying so hard to be patient. He said, "Mom, what is that called when you are naked?" as he pointed to my crotch. I started feeling faint. I was not ready for this. I am an adult. I am educated. I am a Registered Nurse. I could not handle this question from my five year old baby boy! I said, "It is called a penis on you." He said in a frustrated, know it all tone, "I know! I am talking about you!" I couldn't say it. I am immature. I am not ready for this. I could not say it! I hesitated and then I gathered up all the calmness I could find and I said, "It is called the female bum." I couldn't believe what came out of my mouth. I lied. I am thirty two years old and I couldn't say it! The female bum! He was quiet after that and went right to sleep. I went down stairs feeling sooooo guilty. I am the worst mother in the world. I know what I was supposed to do, but I couldn't. I shared the story with Donald and of course, he had a great laugh. I laughed too. All the while I had tremendous guilt. What is wrong with me. You are supposed to be honest. If he asked the question, I should be able to answer it. All night the conversation haunted me.
At 5:30 a.m. I got my usual wake-up call from him in the bathroom. I said to him, "Remember, last night when you asked me what the female bum is called?" He said, "Yes." and looked up at me squinting with sleepy eyes. I said well there is another word, "It is called a vagina." He looked up at me more awake this time and said, "Oh cool, it rhymes with China!"