What does a tattoo of 13 on the nape of the neck mean?

The number 13 tattooed on the nape of the neck may hold personal significance that is not immediately apparent, such as a birthdate, so one should not jump to conclusions. However, it is possible that the tattoo is a sign of affiliation with the MS-13 street gang.

MS-13 gang members are known to sometimes display the numerals "13" or the Roman numeral variant "XIII" on various parts of their bodies. A tattoo of this type should not be automatically considered a sign of gang involvement, however. Aside from the possibility of 13 representing a date of personal significance, it is also widely regarded as an unlucky number and is embraced by some subcultures.