"A non sequitur is a literary device; in comedy (as opposed to in formal logic), it is a comment which, due to its lack of meaning relative to the comment it follows, is absurd to the point of being humorous. Its use can be deliberate or unintentional. Literally, it is Latin for "it does not follow"." Link.

This is a complete list of all the non sequiturs I have in my /dev/random box in the right column.