Non sequitur literally means 'not in sequence'. A non sequitur is a statement which doesn't logically follow previous statements, or where logic is scrambled. This isn't quite dissembling, but it's similar. Describing something as a non sequitur is in fact a qualitative statement, meaning by inference that the person doesn't follow the sequence of the events in the statement. Non sequiturs are commonly used in humor, and as an illustration of faulty logic.
Examples of Non Sequitur:
|I think, therefore I'm a duck.|
He lived a sheltered carefree life on the army's firing range.
I would have come sooner, but I got into a gun battle with a marmot.