From Wilson Gray on ADS-L on the 6th, in a discussion of a joke that turns on a structural ambiguity, a totally different joke of this sort:
A drunk is staggering along the sidewalk muttering to himself, “It can’t be done! I couldn’t do it!” A passer-by comments, “Damn, man, you all fucked up!, It must have been something terrible! What couldn’t you do?!” The drunk answers, “Drink Canada dry!”
The joke doesn’t quite work in print like this, unless you use all-caps, the way artist Richard Prince did in this “joke painting”:
Untitled (Drink Canada Dry), acrylic and silkscreen on canvas, 1998
The joke of course also works fine in speech. (Early occurrences in print have only either Canada Dry or Canada dry, with text that points the reader towards the other.)
Two things: the joke and its history