Famous Movie Lines That Were Actually Improvised
Zoolander
In Zoolander, Ben Stiller has many interactions with David Duchovny’s J.P. Prewitt that were just too good to leave out of the finished film.
In one said moment, Duchovny’s character delivers a long monologue to answer Stiller’s question, only to have Stiller as, “Why male models?” all over again.

Zoolander
But given Duchovny’s funny reaction and how hopelessly stupid Stiller’s character was supposed to be, the error worked out just fine in the movie.