Yes, rabbits can growl. Tell your friend to go to www.rabbit.org and do some reading. By putting her hand in the cage the rabbit feels threatened and is trying to protect itself. Bunnies have excellent vision....except straight on..their eyes are located at the side of the head so that space in between the eyes is blind........it could be that the rabbit knows something is in front of her but isn't sure what it is..or your friend has mishandled the rabbit and the rabbit is afraid of her.

Cage doors should always be left open and the bunny should be allowed to decide when it comes out and when it goes back in.....they should not be manhandled and put in the cage or removed for the cage...or a carrier for that matter. Remember that rabbits are a prey animal and and most are afraid to be up and off the floor because they know they are vulnerable.

Tell your friend to lie down on the floor and spend a lot of time there with the rabbit. Rabbits are intensely curious animals and he will come over to check your friend out. It could also be that the rabbit hasn't become accustomed to her yet and for a rabbit to be your friend THEY have to TRUST YOU first....rabbits are not like a cat or dog and do not automatically love you just because you've taken them home....the trust has to be earned and then a rabbit turns in to a delightful and fun pet.

Another reason why a rabbit might act aggressive is if it has NOT been neutered.... The bunny's horomones could be driving him a bit crazy abd since he/she is not getting any "relief" that's enough to make it cranky.

Good luck...chances are pretty good that if the bunny is mean it is the fault of the owner doing or not soing something correctly.