If you've been left puzzled at why your neighbour or colleague is looking more like Fu Manchu than usual this month, they're (probably) raising money and awareness for men's health.
So by now, Mo Bros - as they're known - should be past that awkward stubble stage, and have chosen a definite style for their facial hair.
"I'm seeing a lot of truckers around, and I've actually got one myself," said Jason. "It's the moustache along the top lip and then it comes down either side right down to the chin and that's quite popular at the moment."
Facial hair is notoriously aging, turning young men into those who look wiser than their years and I felt I 'moustache' asked the Belfast man on how to make sure your choice goes with your face.
"The thing about moustaches is that the younger you are, the smaller the moustache you suit," he explained.
"So older guys can suit big bushy complex moustaches but the younger guys tend to stick with more simple versions."
Whether you've opted for a Charlie Chaplin or a Tom Selleck, growing a moustache isn't difficult.
It's the next bit that's tricky- keeping it groomed and clean, and not ending up like a character from a Roald Dahl book.
If you're eating or drinking you'll suddenly realise that the food and drink is going to get into your moustache so you do need to clean it every day.
"For people who aren't used to having facial hair, they might find it a little bit itchy, so what they should do in that case is use a little bit of hair conditioner on it. That will soften down the hairs and make them less itchy."
His final tip involves one of those little trimmers often seen on infomercials - "When a moustache grows it'll grow in over your lip so you will need a little trimmer just to line your top lip and keep it nice and tidy."
The once beloved moustache, which was a firm favourite in the 1970s and 80s has gradually fallen out of favour with most men but there is a pocket of hipsters who sport their more unusual facial hair all year round.
For some it's about minimal effort (i.e. can't be bothered), but for others moustaches have become part of their funky wardrobe choices, and Jason believes Movember has a hand in making taches trendy again.
"It's getting us guys to do something that's a bit different in terms of how we look, and I know it looks silly but I think it also looks quite cool and it's interesting to see these younger people with these Tom Selleck moustaches," he added.
"It brings me back to the 70s when I grew up and I think it's quite a style statement as well."
Jason will be among those judging the best mo at the ManTime fashion show in Belfast on Thursday evening, when he'll be examining whiskers from contenders including Belfast Giants players.
"We'll be looking for attention to detail, we'll be looking for guys who have committed to something which is clearly making them look quite strange, because let's not forget moustache is our ribbon.
"Whenever you see people supporting charities they have different coloured ribbons, well the moustache is our ribbon, so the more care and attention they've put into that the more we'll appreciate it and the more points we'll award to it," he said.
Some of that money is spent in Belfast in terms of research for cancer, so while it's as global charity, we do benefit from it locally as well.
So Movember provides much amusement, but it is essentially a way of getting the word out to men about how important it is to keep an eye on their health.
"That's why we do it, it's to get the word out, and also to raise a bit of money that could be spent on research.
"Moustaches aren't actually in style at the minute anyway so definitely get it shaved off at the end of the month and that's you complying with the final day. You're raising money, so the people who've given you cash would like to see."
And if you're two-thirds of the way through your Movember effort, soon your thoughts will be turning to what's next in facial hair.
Grooming guru Jason says no facial hair or maybe just a light stubble "but a moustache on its own is definitely not in style".
And you can upload your mo to our Movember gallery!