As an adjective, it pertains to activities involving Mexican illegal aliens in the United States. The earliest known recorded use in this way is by John Steinbeck in the novel Sweet Thursday, the sequel to Cannery Row, with the sentence, "How did he get in the wet-back business?" It was originally used as a verb in 1978 in Thomas Sanchez's Hollywoodland with the meaning, "to gain illegal entry into the United States by swimming the Rio Grande".[8]