Okay, but how about Henry wears a human costume?

Oooooh… that has possibilities

One other character I know who got turned into a donkey (well, mule but close enough)
https://www.youtube.com/watch?v=3Kb5L55J55k

I’d forgotten about this one! Thank you ^^

Perhaps he gets to be a centaur this time? A donkey one?

how about midsummers night dream?

Alright, speed round, two minutes for every notion I can jot down, let's goooo~

Donkey piñata
Donkey basketball
The Ass in Lion's Skin
Ooh, related... who was it... Puzzle in the last Narnia book? I wanna say there was an... ape or something with him for Louis...?
Donkey Cabbages
Pin the tail on the donkey

Annnd time. ^_^o Here's hoping there was something usable or at least mildly entertaining in there.

I mean, there's Jaccus.

We had Jaccus last year, I think Puzzle was the backup choice for this year.

Or was it Rabadash? Rabadash and Aslan hasn't been trotted out yet, I believe.

The ass gets made an example of in several Aesops too.

You know what; tie a conical party hat on Henry's head, a white sock under his jaw, a long mop head as a wig, a sprinkling of mustard powder for body colour and he's the perfect grumpy Auris. Dress Louis up as Oberon at the same time and Moth gets to offend EVERYONE. Or with the right adornments, Skurl, if the backlash would be too much of a risk.

Depending on how much Henry's changed, he could go as his own spin on The Wolf-man, The Donkey-man.