There's hardly anything funnier than when an animal thinks he's people.
Take Polo the Macaw here, for example. Doesn't he laugh just like an evil villain plotting world domination? What's even more amazing is how he shrugs his shoulders, "stomps" his feet and appears to double over with laughter, just like we do when we can't stop laughing.
And just wait for his exasperated sigh at the 44 second mark. It's so endearing and humanlike, it almost makes you forget how truly villainous he sounds. But perhaps that's all part of his evil plan?