I just watched the special features on this movie and there was a particualr story that the director Mark Rydell told which I thought was funny.
It was when they were having lunch together and during the lunch Duke got up to go to the bathroom. Upon his return his 1 pant leg was wet on the side all the way down. Mark asked Duke, "What in the world happened?" Duke looked and him and sighed, "It happens to me alot in the bathroom, everytime I am standing there and some guy turns to me and says, your John Wayne!!" and he made a jester as to show the gentelmen peeing on Duke's leg!!! I had never heard that story before and thought it was quite funny.