With the new killer bunny behaviour, you can make a hybrid "Toast" killer bunny that is still hostile. This is likely not intended, but could be.

How to Reproduce:

1. create a new super flat creative world with cheats
2. Spawn a killer bunny
3. /give @p name tag 1 0 {display:{Name:Toast}}
This gives the player a toast name tag
4. Rename the killer bunny.
5. You will have a bunny with the toast skin and it will still be hostile.