David on the importance of keeping the bathroom door closed

David offered a rather lengthy explanation of why we keep the bathroom door closed.  

To summarize: 

 If we leave the door open, Mary will get in and fall in the toilet and get lost down, down, down in the pipes.  

Then he told us that, if Mary were to get lost down, down, down in the pipes, we can buy a new baby.  (But I think we will just try to keep the door closed.)