Director - Farrelly Brothers

There are many scenes in the film that show how moronic and simple-minded best friends Lloyd Christmas (Jim Carrey) and Harry Dunne (Jeff Daniels) can be but this one showed how annoying they can be on car trips - and it was entirely unscripted.
Even hitman Joe Mentalino's (Mike Starr) hissy fit reaction to the scene was unscripted, which makes the scene that much funnier.