There are two donkeys. One says to the other, 'I'm giving up acting.'
'Why?' says his friend.
'I was up for the main part in a joke,' says the first donkey, 'and they gave it to some chicken. A chicken - I ask you. All I had to do was cross a road.'
'That's terrible. What did you do wrong?'
'They said my acting wasn't good enough - they couldn't see my motivation.'