Filipino Gangs
A tattoo of a Question Mark ? located in and any part of the body are part of an infamous Filipino gang BNG or Bahala Na Gang ( Come What may ). Who are very violent and dangerous.

North American
A tattoo of three dots in a triangle, usually found on the skin between the thumb and forefinger, stands for "mi vida loca" ("my crazy life"). Along with the pachuco cross, it is a popular "generic" tattoo among Hispanic teenagers, and has no direct connection to gangs. The tattoo has also been adopted by Vietnamese teenagers, along with the similar interpretation of "toi khong can gi ca" ("I need nothing"). See Three Dots Tattoo.

A teardrop tattoo is said to indicate that the wearer has killed or a friend of his was killed in prison. It is worn by the eye.

A tattoo of a shamrock is associated with the white supremacist prison gang founded in California known as the Aryan Brotherhood. The Aryan Brotherhood is also known to use 12 as an identifier, with the 1 symbolizing the letter A, and the 2 symbolizing the letter B. Another white supremacy gang, the Aryan Circle, uses 13 as their symbol, with the same derivation.

A tattoo of an Ace of Spades was mainly adopted by the Aco Town and Asian Boyz gang, but has been widely used by Asian youths in California. Often an "A" is placed in the middle of the spade: the "A" symbolizing Asian and the spade symbolizing thievery.

A tattoo of the number "13" indicates membership in the Mara Salvatrucha 13 (MS13) gang or affiliation with Surenos (Indicating membership in a southern California Street Gang). The Mexican Mafia uses MM or a hand (normally a black hand) and are sometimes affiliated with California-based street gangs known as the Sureños. A tattoo of the number "14" is associated with the prison gang Nuestra Familia from Northern California, and associated with California-based street gangs known as Norteños. Surenos and Nortenos are Mortal enemies in prison and the on the streets. A tattoo of "13 1/2" means 12 jurors plus 1 judge plus 1/2 a chance. It is a common practice for California street gangs of all races and ethnic backgrounds to have the telephone area code of their neighbourhood tattooed, e.g. 213, 818, 310, 714, 415, 619; with the frequent changes in California area codes, this can quickly become outdated.

Russian
Russian criminal tattoos have a complex system of symbols which can 'read' to give quite detailed information about the wearer. Not only do the symbols carry meaning but the area of the body on which they are placed may be meaningful too. The initiation tattoo of a new gang member is usually placed on the chest and may incorporate a rose. A rose on the chest is also used within the Russian Mafia.

Tattoos done in a Russian prison have a distinct blueish colour and usually appear somewhat blurred because of the lack of instruments to draw fine lines.

In addition to voluntary tattooing, tattoos are used to stigmatise and punish individuals within the criminal society. 'Grins' may be placed on an individual who fails to pay debts in card games and often have very blatant sexual images, embarrassing the wearer.

The four suits
Spades - the "suit of thieves" (particularly where the symbol appears upside down).
Clubs - another "criminal" suit.
Diamonds - the "chummy suit" (i.e. stoolpigeons and informers). This suit is usually forcibly applied.
Hearts - a sexual symbol. It may mark the wearer out as a "passive homosexual" within the prison.