Here's a precursor to "420" as marijuana slang, fully 56 years earlier than its supposed origin in 1971. The text reads, "Cabbage soup is made in a lidded pot. Yes, but the lidded pot falls into the cabbage." "Lid," "pot," "cabbage," and "420" are all euphemisms for cannabis. From 1915, printed in an issue of Le Rire the following year.