I've read so many variations of this joke/tale. It may have happened at sompe point in time at some place and people maybe localised it to make it more relevent to them. The one I've seen most is between the yanks and the canucks but I've read some between the yanks and the brits, danes, aussies, hell even the damned japs. Always seems to be against the yanks though, gotta tell you something about how the world percieves them.