They don't really mean anything.
It was just something fun someone decided to do one day by sending a gift to someone with the phrase "I've been kissed" and asking them to pass it along...kind of like a chain letter. The "bunted" one was another such "game". It essentially means "head butted by a kitty", a sign of affection.
I believe both were the result of an initial "game" called "I've been frosted" where people were sent a snow flake icon in PM and asked to put it in their signature with the phrase "I've been frosted" and to send it to anyone on the forums who hadn't been "frosted". It was cute and fun. However, it gave way to several other ones such as the "kissed" and "bunted" as well as others.
The moderators finally asked people to stop because it was becoming overwhelming and the signatures were getting too big with all of the text and icons in them.