A non sequitur (IPA: /nɑn 'sɛkwɪtə(ɹ)/) is a conversational and literary device, often used for comical purposes. 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 or confusing. Its use can be deliberate or unintentional. Literally, it is Latin for "it does not follow."

(http://en.wikipedia.org/wiki/Non_sequitur_%28humor%29)