I'm not really sure about the French, i don't know enough to decide which one is correct. I asked my French teacher (yes, E_net4, i've been studying French, it's one of the 3 foreign languages taught at school (actually, the 3rd is a choice between French and German, but yeah)) about this one, so for now, i'll go with her suggestion.
Anyway, the joke? It's a pun - the phrase "le code Morse" could either mean "Morse code" or "walrus code". Hence the comic being in french.
And much of the whole point of #09 was to not have a punchline, instead be just wholly weird. Not one of the better NHE-s, but you can't win 'em all.