My son and I have been having a discussion on what age is too old to be trick or treating. I have a few suggestions for him.
If you are able to legally drive around the neighborhood, you should probably stop walking around asking for candy.
If you are taller than most of the parents in the neighborhood, time to stay home.
If you have a full beard, time to let go.
If you are old enough to be in a relationship (aka Facebook Official) on Facebook you should probably stay home and pass out candy with your significant other.
These aren't hard and fast rules, just some suggestions.