What a man with a well-groomed facial feature gets when he provides oral stimulation to the female genetalia.
"man, I really like having this moustache. But I'm tired of it becoming a moistache when I go down on chicks. Especially when I can't find running water for a few days"
"The well endowed moustache man was inexplicably rewarded with a moistache after pleasing the old woman's nether-regions"
Perspiration on the upper lip.
It is so hot out side that I have a moistache.