I used to own a rabbit that would open up a big can of whoopass on any cat he encountered. He was a 20lb flemish giant.
My ex used to own a lop-eared that would try to put whoopass on all the dogs in the neighborhood and then beat feet back to the house if they came after him. He was especially notorious for finding the ones on a chain and then jumping just in and out of the max chain circle-radius.