Did you know? Do you care? Butt sniffing is a very natural, instinctual, and basic form of cat-to-cat communication. Strangely enough, it is how cats greet and get to know each other, along with sniffing of the chest and neck. Even cats that know each other well will sniff butts to "see what's new" and reinforce their bond and communication. Behaviorists suggest that because the butt sniffing routine is a normal part of cat behavior, it's best not to interrupt it if the cats seem friendly. Interrupting this behavior is equivalent to you stopping a friend from shaking hands with someone they are meeting: it can annoy or upset the friend and can make the introduction awkward. In fact, lack of this butt sniffing communication between cats can create stress between the cats.