They're about the size of a household pet, but they are not to be kept as pets.
Quokkas are also known as being very photogenic, because a simple Google search will bring up tons of pictures of people taking pictures with quokkas.
Unfortunately, if you were in Australia and saw a quokka, they may enjoy taking a picture with you, but you have to be careful to respect their space!
This is because quokkas are considered an endangered species.