1.79. Hans and Fritz are German spies during World War
II. They try to enter America, posing as returning tourists. Hans is
immediately arrested. (JM, originally from How Come —
Again?)

1.79 answer: Hans and Fritz do everything right up until they’re filling
out a personal-information form and have to write down their birthdays.
Fritz’ birthday is, say, July 7, so he writes down 7/7/15. Hans, however,
was born on, say, June 20, so he writes down 20/6/18 instead of what an
American would write, 6/20/18. Note that this is only a problem because
they claim to be returning Americans; there are lots of other
nations which use the same date ordering.