Originally, in the early 18th century, junk meant a lump or piece of anything. The etymology is uncertain, but the OED ventures it perhaps derives from the word ‘chunk’. By the late 18th century, ‘old junk’ had become a nautical term for old or useless rope. The modern meaning for rubbish or worthless stuff only dates from 1913, according to the OED. From the early 1920s, junk is also US slang for narcotic drugs in general. Since the 1980s, junk also acquired a new slang meaning for male genitalia, which received a massive boost in 2010 when a young software engineer named John Tyner took a video with his phone of US airport security patting him down. Tyner’s remark, “if you touch my junk, I’ll have you arrested” went viral. See also Junkie/junky.