(A couple notes before I begin. First, this is strictly about mannerisms. I may cover actions, habits, and vocal patterns at a later date. Second, I’m an advocate of everyone just being themselves no matter their mannerisms. This isn’t a how to guide, but simply observations I’ve had as well as others. Thirdly, not every man has these mannerisms, just a slight majority.)
This all started with beer. Or actually it started with me looking at how this guy held his beer. He probably didn’t even realize, but how he held his beer told everyone in the bar: I am masculine. Curious, I decided to investigate masculine mannerisms. Some of these are obvious and others less so.
As a general rule, men like to take up space. In chairs they tend to slouch more, and spread out with their legs and arms. They keep their legs apart, and employ the ankle resting on the leg method of crossing their legs.
Additionally I’ve commonly noticed men slouch down in their chair and then stick their feet straight out crossing their feet at the ankle.
General observation for mimicry: Arrange yourself as though you had no bones in your body. Drape yourself over the couch or chair or against the wall like you are all floppy, and don't worry about personal space.
When women walk they do this one-foot-after-the-other-in-a-line walk (think balance beam). Men on the other hand walk with their feet apart and side by side (following two parallel lines) and surprise surprise they don’t sway/switch their hips. Additionally a guy's heel is the first thing to touch the ground, and his toes generally stay up longer than a woman's. (Women, used to heels, will touch down first with the ball of their foot.) They walk heavy, with purpose, confidence. Some might refer to a masculine swagger, but I have yet to figure out a swagger which doesn’t make me look like an spaz or like a cocky something or other.
Unlike women who may put more weight on one leg, men will stand with equal weight distribution on both feet. When a guy feels threatened, he'll get "bigger" to try and scare the threat, as opposed to women who generally get smaller as to not be noticed. Lean. Lean against walls, door frames, vehicles (make sure they’re not moving when you do this).
Women tend to emphasize their points with their hands, men tend not to. Men keep their hands down and low. They stick their hands in their pockets, but to do that you need pockets you can actually fit your hands into…stupid girl jeans. In an interview with Felicity Huffman when she was playing in Transamerica, she said she moved her hands like she was underwater, which made them seem bigger and more mannish. Avoid hands at hips at all times, unless you are David Caruso…who you are not.
Men aren’t as careful when they hold things, so many men (and a few women I’ve noticed) hold their beer bottles by the neck with a few fingers, when they’re taking sips. For larger gulps, they hold their bottles in a typical position at the label.
Smirking, it’s not just for lesbians! When guys smile their grin is a bit asymmetrical, sort of almost lopsided. Men tend to be more cheeky with their smiling than women, and typically don’t react as “large” as women do. They want to seem unfazed and in control of everything happening around them.
They’ll crane their head up in response of a threat or acknowledgment and use more non-verbal communication than women. Men clench their jaws when doing manly things.
Guys look confident. They don't look apologetic, hesitant or shy. Even reserved guys tend to have an air of self assurance.
They aren't too emotionally expressive most of the time, but when they are, they wave their hands and arms around a lot (dynamically, not girlishly. They don't keep their hands close to their body---men fling them out.) They don't try to be contained or quiet about it---upset/excited guys get very demonstrative.
We could get into the cruder aspects, like “package” adjustment, or scratching, but oh hey I just did!
Take up space. Be less expressive.
QBP: "When women are depressed, they eat or go shopping. Men invade another country. It's a whole different way of thinking." -Elayne Boosler
I observed a lot of these mannerisms and got the rest from this site.