According to Jewish numerology, the word "chai" (meaning "life") adds up to 18, so in Jewish traditions, 18 is considered a lucky number. Donations to charities or gifts to bat / bar mitzvah children, marrying couples, and new babies are often made in increments of 18 for this reason. The word "chai" might be familiar to even non-Jewish people from the toast "L'chaim" (meaning "to life!"), the inspiration for an eponymous song from the hit 1964 Broadway musical Fiddler on the Roof.
Stills from Californication are used when the students Google Sam.