When having anal sex, pull out your penis and wipe it just above ur partner's top lip resembling a dirty mustache.

it is often confused with its cousin the dirty sanchez where you use your finger.

When there is no doo in your girls boo, just jam two fingers from both hands(double barrel)in her butt, and then swish them around in her mouth. Then, smear it across the top of her lips from both sides, and you have yourself a dirty gallegos.

When someone not of Mexican heritage attempts to pull off a mustache but epically fails and just looks stupid.

It can also be if a person is just too damn lazy to shave, but lets all facial hair grow out along with the stache. If this is the case, it may be acceptable.

a gross mustache typically grown but douchebag guys who think that it's nice to shut doors on and ignore girls. and who like to go to business class still drunk.

latin: Clunis Concubitis Barba
After a man and woman engage in anal sex, the maile removes his still-erect member from his partner's rectum and rubs it along her upper lip, thus creating a sort of fecal mustachio supposedly reminiscent of a scraggly Mexican mustache, or bigote.

dirty mustache originated from birkenhead.

an unthick poopy dirt looking mustache. looks like someone smeared dirt around there face. Its ugly and digusting