The tan that a male with thick and full facial hair receives from prolonged exposure from the sun. Shaving one's facial hair after being in the sun for a long time results in a pale area on the face where the facial hair was prior to shaving.
Any tan outline that results from shaving facial hair after getting enough sun show a visible difference in skin color causes the individual to have a "man tan"
Friend: Looks like you got a lot of sun today!
You: Yeah I did! I'm going to go shave my face now, so I can show off my man tan.
Friend: Is a man tan is a good thing??
You: Duh! Just wait until you see my man tan, you'll be like: Winning!