The mailman joke

One night while the parent's were having sex a kid walked into the room and saw his parents having sex. The mother jumped up and exclaimed, go in your room billy, I will be right in there. After careful consideration, the father decided that it would be best if he went in and explained it to billy.

Billy, what we were doing is making you a baby brother. Oh goody, goody cried billy. The next morning as the father came down the stairs he found billy sitting at the bottom of the steps.

What are you doing up billy he asked. I am thinking about my baby brother said billy and with that his father left for work. Late that evening the father came in from work to find billy sitting on the steps but crying this time.

Why billy, what is wrong? This morning when I left you were happy about getting a baby brother and now you are crying. Well, I was happy daddy but then the mailman came and ate my baby brother all gone.