They love to do that, gnu. ;-) It's like climbing Mount Rushmore, they need some relief when they reach the top.

I know that these birds love to sing along with recorded music, but that's okay. As for the bites, well, not a big deal unless the bird bites your lip or something. One girl I knew (who was an idiot) taunted her budgie one day by sticking out her tongue at the bird, and the bird promptly bit the end of her tongue, eliciting a most satisfying screech from its owner.