As Hager explained, a group of Californian teenagers ritualistically smoked marijuana every day at 4:20 pm. The ritual spread, and soon 420 became code for smoking marijuana. Eventually 420 was converted into 4/20 for calendar purposes, and the day of celebration was born.

What does 420 have to do with getting high?

The number 420 has become a secret code among potential roommates and people on dating websites, a way to covertly let someone know that they welcome marijuana into their home or love life.