Jailhouse is a shorthand term used to describe a style of tattoo work seen practiced by incarcerated prison inmates on one another, and typically characterized by fineline/single-needle black/grey lines and shading. The imagery is often comprised of religious iconography, voluptuous women and symbolism to connote gang affiliations and allegiances of place or origin. Various marks (e.g., tears falling from the corner of the eye, or spider webs on the elbows) may also be representative of time served or crimes that have allegedly been committed by the inmate. Because tattooing is almost universally prohibited in prison facilities, the work is typically done underground using crude materials (e.g., inks made from the residue of items burned or shoe polish) and makeshift tattoo machines (cobbled together with the shaft of an ink pen and a small motor such as one taken from a cassette recorder) or done by hand.
Despite these severe limitations, there are many examples of extraordinary work that have been done in prison, and jailhouse tattooing was the forerunner to the more expertly executed fineline black/grey work and portraiture popularized by artists such as Jack Rudy, Freddy Negrete and Mr Cartoon in Los Angeles.
The term "jailhouse" is also used in a derogatory sense simply to refer to badly-executed tattoos or tattoo work that lacks sophistication.