The Red Button
The Red Button is an imaginary device which Retriever II occasionally "threatens" to use. It has one purpose: destroy MFGG when pressed. As a result, many forum members and RII himself tend to joke about it, and drawings of RII using the button (and of the aftermath) are posted every once in a while.
Even if the Red Button did exist, it seems unlikely that RII would actually use it; in fact, he spent a good deal of effort restoring MFGG from The Great Mistake. Some people have compared The Split of 2010 to the pressing of the Red Button, but that act was more like an orange button, since it didn't permanently kill off MFGG.