From WhatPort80

The essence of image macros.

A phrase originating in the Something Awful forums to describe images often used on USENET before the popularization of forums on the internet. An image macro is a photo or picture with a (usually) witty phrase superimposed over it, most commonly in white 72pt Impact with a black five pixel stroke. Often used in flame wars and a fundamental feature of gif wars, they convey a humorous message of disdain towards the original poster or the entire thread.

The recipe for a good image macro is deceptively simple. All you need for a good macro is a hilarious picture with a hilarious caption. Both elements are required for a perfect macro, and matching the two is often challenging. As with all good things, their impact is dramatically diminished with overuse, and most image macros suffer overuse within hours of their debut. The majority of internet users are oblivious to this fact, and will continue using them well past their date of expiration.

Traditionally, the process of producing image macros has itself offered a passable barrier to idiocy, and the few seconds required to modify a picture offered competent authors a vital few moments of reflection in which they might abort a potentially embarrassing project. Fortunately, certain leaders of enterprise have obliged the mouth-breathing public by developing web sites that will slap an obnoxious and obvious caption on any old image that is run through it.

Gallery

I regret to inform you that you were just pwned. Sorry.	You are introducing unnecessary drama into the situation.	Due to the shocking nature of what just happened, I am completely speechless.	I am dumbly referencing pop culture to let you know things I could just say myself.
Dogs are funny.	Despite my claims of quitting forever, your stupidity has baited my continued interest.	If at first you don't succeed, try, try again.	I am doing something homosexual. I am heterosexual. Ergo, I am cool.