My ten-year-old nephew (who later became a space/time philosopher) had a favorite riddle:
Mrs. Bigger had a baby. Which was bigger?
The baby was a little Bigger.
There is a musical parallel: When is a triad not a triad?
When you take one note away and position it on the piano so that it sounds like "something else."
In the spirit of the Classical sonata as auditory game, this is what happens in piano works by Haydn, Mozart, Clementi. We have grown so accustomed to assuming triads where they actually are not present that we miss a tremendous amount of double entendre.