And last but not least, I've searched the book of Spanish language I had when I was in 12th grade ("Por el mundo hispánico 5", J.Villégier & F. Molina, Ed. Hatier) and there are the chorus and 2 verses of "La cucaracha" (along with "Adelita" and "La Valentina") and it goes:
La cucaracha, la cucaracha/ ya no puede caminar/ porque le falta (2), mariguana* que fumar.
with a note : * o marihuana, nombre vulgar del cánamo común. Fumado como tabaco, esta droga produce embriaguez y trastornos mentales.
But in 12th grade you're supposed to be 17/18 years old.