A knuckle tattoo is a kind of tattoo that most commonly uses two groups of four-letter words or one eight-letter word.[1] It is not necessarily a prison tattoo, as sometimes believed, but remains an unpopular form of tattoo—alongside hand tattoos in general—due to the difficulty of hiding it in situations such as a formal setting where it would be seen as crass.[2] Some people also use their knuckles to tattoo drawings and images, sometimes in groups of four, such as the four symbols of a deck of playing cards to signify good luck, or astrological symbols.
Robert Mitchum's character Reverend Harry Powell wears LOVE / HATE in the 1955 film The Night of the Hunter.[3]
In The Blues Brothers, the main characters have JAKE / ELWO/OD on their knuckles.[4]
Musician Flea wears LOVE / LOVE. Professional wrestler CM Punk wears DRUG / FREE.[5]
In sailor tattoo traditions, deckhands may get HOLD / FAST as a charm to support their grip on rigging.[6]