Usually used to mean acting and dressing flamboyantly for women, but the word's roots actually lay in the competitive eating circuit.
To peacock is to thrust one's gut outwards in a flamboyant fashion. The peacocker will parade about the room with his gut out for the world to see. It's a sign of pomposity often seen after a hard fought victory. More and more though, arrogant, up and coming eaters will peacock in public settings or at a non-competitive eating function. This is offensive and occasionally leads to fights.

While there's nothing wrong with a little peacocking here and there, one should not abuse their gut and peacock too frequently. One should respect their gut and the guts of others by keeping their own gut to themselves. Only peacock when you have earned the right!
Slugger peacocked all day, everyday for a straight week, needless to say, Acun and Big Kahuna were outraged and challenged him the next day at the local Golden Corral.
by The REAL Acun October 15, 2010
A man who dressed up, done hair and posed for a profile picture to try make himself look good but resulting in looking like a complete melt.
me: dude have you seen this pussys profile pic.
friend: i know man what a fucking Peacock.
by jerkcrackhead November 19, 2010
A 3000 year-old teacher at Williamstown High School, NJ, who mispronounces many words like robot (robut) and alright (ehhwit). She teaches C++, some weird computer language that nobody cares about. She saw Jesus in the year 0 be born.
Peacock-

"Ehhwit" class, let's talk how a computer is a "robut."
Peacocking means dressing for attention. Just like Peacock's use their feathers to get a mate.
Peacocking is meant to make opening a girl easier, but if you're not congruent with your look (like, if you look like you're gay and you try to hit on a girl), wires are gonna get crossed somewhere and you're gonna blow yourself out.
by The Light August 26, 2006
The act of a male politician waving his tiny dick around in order to grab the attention of his orange neon god.
By filing the failed lawsuit against Vice-president Pence, Senator Josh Hawley was shaking his feathers and peacocking for the lame duck loser president.
by Bugszy January 2, 2021
inserting both thumbs in a girls anus while she is bent over and spreading the remaining eight fingers like a fan representing a peacock's tail feathers
Girl, have you ever heard of The Peacock?
by creek11bravo June 13, 2010
1) A song by Katy Perry from her album "Teenage Dream".
2) Penis (as implied by the lyrics to the song "Peacock")
Lyrics from Peacock song: I wanna see your peacock cock cock...
by steviep24 October 14, 2010