OMG. 10 years old and he already knew not to spoil movies.
A buddy of mine was twice that age, and didn't seem to know that. A bunch of us went out to a movie together, which was based on a book that my friend had already read.
Five minutes into the movie, he points out a guy on the screen, and tells us, "That's the killer!"
There was almost another murder in the theater that night...