One of the advantages of the relative simplicity and predictability of the Classical style is that it gives composers the chance to play with audience expectations. The simplest example is the interrupted cadence, unexpectedly diverting a perfect cadence and on a larger scale, the ubiquity of sonata form meant that composers could play with the fact that educated audiences would know what to expect at key moments such as the recapitulation. This could be done either to dramatic or humorous effect.
Haydn plays all sorts of tricks both simple and complicated in Symphony 104 (see separate notes) but this page contains some simple examples of Haydn’s playfulness.
One of the most obvious and famous tricks that Haydn plays (other than the sudden chords in the Surprise Symphony) is in the last movement of his String Quartet Op. 33 No. 2 ‘The Joke’. See full score here.
Haydn begins with a simple Rondo idea that (as you would expect) is repeated many times:
By the time we get to the end of the work we know how this A section goes very well indeed and this allows Haydn to play with our expectations. He is helped by the fact that the first two bars is a perfect cadence and therefore can work equally well as an ending. You can see by looking at the score that Haydn starts inserting bars of rest in between each subphrase of the rondo idea. Sixteen bars later, once this new version of the theme with two bar gaps bewteen each two-bar subphrase has finished the audience might reasonably expect the piece to be over but after four bars rest (having given the audience time to start applauding wrongly) Haydn plays the first two bars of the theme again. As it turns out this really is the end, but the audience is left wondering whether to applaud again or whether to wait and see if there is any more.
End of movement:
Haydn also plays a trick on his audience in an earlier quartet (Op. 20 no. 1). Here the joke is a bit more subtle and requires the audience to have some sense of the keys and modulations in the piece. See full score.
The Minuet third movement starts in Eb major:
The Trio is in Ab major, the subdominant, a common key to which to modulate.
At the end of the Trio, Haydn pauses on a dominant seventh chord of F minor (the relative of Ab). He then returns to the music of the Minuet, but in this ‘wrong’ key of F minor. For anyone paying attention this is obviously wrong, and he tails off (rather shamefaced?) and then reprises the Minuet properly:
In his Symphony No. 47, Haydn plays a wholly different sort of game – read about it here.