Back in 1999, members of the football365 football forum (now mostly found at cupwinkcook.com) formed an e-mail group for some of the forummers to send each other the latest e-mail jokes, attachments, etc. in a convenient way.

One member of the group, Peacock (named so after the Leeds United nickname "The Peacocks"), had the rather annoying habit of posting the latest jokes, attachments, etc. after they had already been posted.

This led to the term "Peacocked".
*old joke arrives in Inbox*

"Peacocked"
by Peacock July 14, 2004
One who dresses spontaneously in an eclectic display of colors and patterns as a means of attracting attention from the public. Single men mostly peacock, when they dress head to toe in obnoxious apparel, decorating themselves in jewelry and name brands, often to get the attention of thirsty hunnies
Tom: “Dax, are you ready to go to Walmart?”
Dax:”yeah, I just need a minute to put on my cheetah print tux and my golden fedora”
Tom: “Damn blood, you’re always peacocking!”
by Blaircon1 June 29, 2018
When a man sticks 12 or more various coloured paintbrushes up his ass in presentation for a female
Todd was totally peacocking for jenny last night. She gave it to him good after that. Blowjobs i mean. Penis sucking and all wile he squirted art out of his anal hole
by Tigerwoodley August 19, 2015
p-cok'd verb; the act of drinking a little too much and remembering far too little....
Dude. I so peacocked when I was in Toronto.
by Friend of the Peacock June 9, 2011
The sexual favor where the handle of a large feather duster is shoved up the ass resembling a peacock
When my wife role plays as a naughty maid, i give her the peacock."
by Vallada March 4, 2009
thumbing a girls ass leaving your fingers facing up and spread as far ass they'll go....works best during doggy style
That girl was diggin my cock already but she fuckin squirted like a waterfall when I peacocked her ass
by Tommy2Fists September 16, 2005
Showing off or dressing nicely with the intent to impress and gain the attention of a member of the opposite sex. The term itself, originating at UNC School of the Arts in Winston-Salem, comes from peacocks in nature who "shake their tail feathers" to attract mates.
Whenever Jerry hangs out with us and his girlfriend, he's always peacocking for her.
by Nikolai1oh3 November 5, 2010