How are babies made????

My best friend and her 5 yr. old son were talking about when his little sister was a baby.  They were having a great conversation when he piped up with, "Mom how did I get made in your tummy"?  She was a little taken aback and did not answer right away.  He then proceeded to say "Did a worm hit the thing and explode and then you puked".  She immediately asked, "where did you get that idea". His response "from a movie I watched at grandmas".  She quickly called her mom and asked what movie she was allowing the kids to watch.   The answer Look Who's Talking.