What does the 13 mean on a biker vest?

What does the 13 mean on a biker vest?

The letter M, being the 13th letter of the alphabet, often is said to stand for marijuana or motorcycle. Generally, it is assumed someone wearing a 13 patch is either a user of marijuana or other drugs, or is involved with the sale of them. The M also has been known to stand for “”methamphetamine””. Jul 29, 2016