Had an interesting experience a few years ago.<p>Me and some friends visited another friend that had a parrot.<p><pre><code>  * When we came the parrot said hello to everyone.
  * One of my friends aggravated the parrot by
    standing on the far side of the cage and making funny
    faces.
  * When we left the parrot said bye to everyone but him.
  * When we came back a couple of weeks later and he had 
    forgotten about the parrot and came too close to the
    cage it tried to bite him.
</code></pre>
Would hardly have believed it if I hadn&#x27;t been there on both occasions.