Dan stood there with a mix of terror and anger. Being a donkey was an odd sensation. After this, Dan knew he'd never laugh at those kids in Pinocchio again. When you were the one it was happening to, it was anything but a joke.
He could tell that this wasn't a joke, Kat had turned him into a donkey for real. It would seem that this also wasn't the spend a few days as one to teach him a lesson sort of thing. He felt helpless and violated. Kat had taken his form and dignity away. He may not have been a great person but Kat wasn't any better! She was playing judge, jury and executioner with him with no apparent consequences for her.
Dan worried that Kat would do the same thing to others! He wanted to know why his parents were allowing this! Dan had always heard things about power requiring responsibility. If Kat could do this to her own brother, she would do much worse to others!
Dan knew this body would keep him from ever seeing his friends again. Heck, it would keep him from doing anything! He didn't want to live his entire life out like this! He deserved a lot better then this! Kat's cruel joke about human being an animal only added insult to injury! Dan didn't try that because he assumed Kat would just laugh at him. The irony of assuming making an ass out of ones self was not lost on Dan. However, the humor of it didn't seem to register when he was apparently stuck as a jackass forever.
"What's wrong Dan? Cat got your tongue?" Kat asked. Her face lit up at her joke. "Why, I guess she does!"
This was it! Dan brayed, leaned forward and grabbed Kat's wand from her with his mouth. At this point, Dan felt that he had little to lose. If Kat was going to do this to him, then he was going to act just like the ass she'd turned him into!