The not-so-secret code has repeatedly snuck into pop culture, presumably meant as an “Easter Egg” for insiders to discover. For example, one of the earliest pop-culture nods appeared in the 1982 comedy Fast Times at Ridgemont High, which famously cast Sean Penn as a high school stoner. In the film, a pissed-off football player (portrayed by a young Forest Whitaker) demolished the opposing team, resulting in a final score of 42 to 0. Later, Oscar-nominated films like Pulp Fiction and Lost in Translation famously set on-screen clocks to 4:20pm. In the television series Mad Men, the agency had a major meeting with American Airlines in a plot line that stretched across several episodes. When the big day came, the camera zoomed in on a date book, and the presentation took place on April 20. Surely not a coincidence for a series that showed characters smoking cannabis in the Village a few episodes later.
The number even pops into politics. In 2003, a California Senate Bill addressed the regulation of medical cannabis, and Governor Gray Davis signed the bill just days after losing a recall election. Brilliantly, an unknown clerk assigned the bill the following number: SB 420.