I remember being stuck
on hold to Vodaphone for ages once and got fed up. I just put them on speaker and then put the phone next to my speaker and went on with my buisiness. As soon as I heard them answer I played the previously cued ( in winamp ) 'Fields of Athenry' at great volume until they hung up.
I have done questionable things.
( Pasanonic WARNING - May induce flouncing., Fri 11 Jan 2008, 18:16, archived)

I had some ol' service desk trout who put me on hold 7 times in just over ten minutes
So I asked her to hold and subjected to to about two minutes of me going 'Doo dodo do doobie dodo' before she gave up.
( riverghost www.b3ta.com/questions/imagechallenge/post262552, Fri 11 Jan 2008, 18:32, archived)