Wikipedia:
For a teaching by a pope or ecumenical council to be recognized as infallible, the teaching must make it clear that it is definitive and binding. There is not any specific phrasing required for this, but it is usually indicated by one or both of the following: (1) a verbal formula indicating that this teaching is definitive (such as "We declare, decree and define..."), or (2) an accompanying anathema stating that anyone who deliberately dissents is outside the Catholic Church. For example, in Munificentissimus Deus, Pope Pius XII's infallible definition regarding the Assumption of the Virgin Mary, there are attached these words: "Hence if anyone, which God forbid, should dare willfully to deny or to call into doubt that which We have defined, let him know that he has fallen away completely from the divine and Catholic Faith."
I thought this was interesting. This can be used when folks throw the infallible propoganda our way.