When my MIL died last year DS1 had lots of questions and wanted to say goodbye. We didn't want him to go to the funeral as he was only 3.5 at the time but DH and I agreed to take him to the church beforehand and show him nanny's coffin and try to explain things to him. We got there and thought we had explained things really well when all of a sudden he piped up with "are they going to saw nanny in half?"
I suppose a coffin does look similar to those magicians boxes!