A little beard that's just below the lip. Sometimes called a "soul patch" or a jazz musician's beard.
Take a look at pictures of Dizzy Gillespie, Apollo Ono, Gene Krupa, Frank Zappa (imagine him without the moustache).
"He had no facial hair except for a rather evil-looking "white-man hater" that grew from his lower lip like a black orchid and made him look like a drunk who missed the mark on Ash Wednesday." - Kinky Friedman - Musical Chairs