It can vary in size and colour, in the range of 1 cm to 3 inches and a pale white to a deep Caribbean black (an annoying yellow colour is possible but rare).
The facial johnson can be caught in 2 ways: socialising with the infected and being a knob-face.
James: "He's such a knob"
Billy: "I know, has he got a facial johnson?"
Gunther: "Them fucking faggots are corking again!"
Abbey: "They're gonna get fucking bum-nuggets!"
Gunther: "And facial johnsons"