Face jugs have been dated back as early as the 14th century. However, the most famous known vessels today were made by black slaves in the 1800s and were discovered in North Carolina, Georgia, and South Carolina. The exact purpose of the vessels is unknown, but many scholars believe them to be either of practical or spiritual value.

Other names associated with African-American face jugs are grotesque jars, monkey jars, or face jars. Modern interpretations started appearing in the aforementioned regions during the 1940s.

It is also believed that the pots were used to buy and store liquor; the ominous features would scare children so that they were not tempted to try the contents.

source:

http://www.pbs.org/opb/historydetectives/educators/lessonplan/face-jug/