Ultimately, the slanguage of a statusphere is best defined by its native speakers. For instance, if I were to define Bro I might come up with something like:

Bro (Br-owe), n. frat-boy lingo for best buddy, originally a redneck term that had its origins in Vietnam-era military units and was itself a white acquisition of “soul brother” or simply “brother,” then common among black soldiers to show racial solitary, particularly with the Black Power movement, and also touch base with the black churches of the South, whose congregants were referred to as family members, that is, “brother” or “sister.”

In Bro speak, the above would be an example of TMI, too much information. The texting, instant-message generation doesn’t do context, dweeb (dweeb — Bro Speak for “dick with eyebrows.”) My long-winded definition would be a dead give-away for the fatal condition known as geezer head.

Yes, I admit it. As far as membership in the iGeneration goes, your humble servant is well past his sell-by date.

Luckily, I have the Urban Dictionary to guide me, an extremely Bro-centric volunteer effort that seems written between World of Warcraft tournaments, by hands still sticky from the last Chalupa Supreme. Some of my favorite Bro-isms:*

Leave Britney Alone!
Exclamation of breaking-point exasperation. From a hugely popular viral video featuring a Britney Spears fan having a grand mal hissy fit.
Gamer 1: Are you shitting me? Two weeks and you’re still at Level 3?
Gamer 2: Oh for Chrissake, dickweed! Leave Britney Alone! I had midterms!”

Yippie ki-yay, motherfucker!
All purpose expression that can mean anything from “big deal,” to “buzz off.” From Bruce Willis’ signature phrase in the Die Hard movies.
Bro 1: Man, I was up half the night cybering online with these three bitches.
Bro 2: Well, yippie ki-yay, motherfucker!

Wide Stance
A homosexual, especially one in the closet. From the excuse Senator Larry Craig gave when he was arrested for soliciting a police officer in a men’s room, claiming that his shoe touched the officer’s under the stall because he sits with a “wide stance.”
Genevieve is really crushing hard on the varsity QB. Someone should tell her that the dude has a wide stance.
See also con-swerve-ative:
Bro 1: I can’t believe fucking Tommy is a full-on Republican!
Bro 2: Yeah, especially since he has a wide stance. Just another conswerveative like Ted Haggard.

To bullshit loudly, with a lot of hand and arm waving. Derived from the English expression “talking bollox,” literally “talking balls.”
Bro, are you severely fucktarded? You want to tap that, and you go over to the bitch all drunk and loud? I could hear you testiculating from the other end of the bar!

From tipsy. The state of drunkenness when the shedding of the shirt and the pants begins. This may result in a Facebook Surprise, when you find a photo of your freeballing self posted on a fellow Bro’s Facebook page, making you an Interplanetary Facebook Casualty, or IPFC.

chew toy
A hetero update on trick — that is, a person with whom you would have a one-night, but rarely long-term, fling. Interesting as an example of the homosexing of mainstream culture: a once mainly male homosexual point of view has become the norm for young people.
One sorority sister to another: “Do you like my chew toy for the night? I met him on the dance floor.”

To go all award show
To become tearful and emotional, particularly in front of an audience, in the manner of a celebutard (brainless celebrity)
Man, did you see that tool at the Olympics? Goes all award show when they start playing the National Anthem.
See also Kodak Moment — an extra dose of showy bravado and a tendency to push beyond one’s physical limits when being filmed or photographed (popular among skateboarders.)

The opposite of gaydar.
Bro 1: You’re shitting me! Smithers? And Mr. Burns?
Bro 2: Man, you’re so homo-oblivious you’re going to hurt yourself.

Cha-wang and Fap
Both are onomatopoeias, or sound words. Cha-wang is the sound a young penis makes as it springs into an instant, upstanding erection. Fap is the Zen-like sound of one hand masturbating (frequently illustrated with rapid cupped-hand gestures)
Bro, check out this mpeg of Natalie Portman. Cha-wang! Fap, fap, fap!

The Bro Variations
A get-together or party where the attendees are predominantly male is, of course, a Brodeo. A buddy whose main function is to go out drinking with you is a Broski. And if you find that something is missing during winter and summer break you may be suffering from the same condition as this speaker:
“Whoa, I really miss you guys. I’ve become a total broahoic! I need counseling!”

* Ouch! Slanguage doesn’t age well. Please keep in mind this article first appeared in 2007.