Prick

Prick used to be Standard English for penis, from the allusion that it is something that can ‘prick’ or pierce. The OED records its first usage from the late 16th century. From the late 1700s, however, it was classified as vulgar and demoted to slang status, which it has enjoyed ever since. As slang, it can still refer to the penis but can also be a contemptuous term for a man, as in a silly prick, which dates from the late 19th century.