Many of the early episodes of the show feature a sensible-looking announcer (played by John Cleese) dressed in a sensible black suit and sitting behind a sensible wooden desk, which in turn was in some ridiculous location such as behind the bars of a zoo cage or in mid-air (with the desk being kept afloat by small attached propellers). The announcer would turn to the audience and state "and now for something completely different", launching the show's credits.
In later episodes, this was reduced to a split-second stock footage of the announcer saying "And now-" in a similar fashion as was done with its precedessor ('The "It's" man'). It was replaced by a naked pianist.
The phrase is also the name of a Monty Python movie that consists of 90 minutes of the best sketches seen in the series' first two seasons. The announcer uses it several times during the film, in situations such as being roasted on a spit and lying on top of the desk in a small, pink bikini.