Further to the definition referencing M for Marijuana, this originated from the Hell's Angels, who would have a 13 sown/drawn on their denim jackets if they smoked weed.
See Hunter S Thompson's Hell's Angels, where this is mentioned.
Prices shown in USD.
Type your email address below to get our free Urban Word of the Day every morning!
Emails are sent from firstname.lastname@example.org. We'll never spam you.