What is shown
The picture shows a face turned to the side and slightly upward. The eyes are wide open, the pupils are offset, and the mouth is stretched into a silent scream or an astonished "oh." The drawing is done in rough, jagged strokes in black and white, typical of the Rage Comics style: the lines look as though they were drawn in a hurry, and the shading creates a sense of tension and chaos.
It's the combination of bulging eyes, raised eyebrows, and a twisted mouth that makes the expression unambiguous. The viewer reads the emotion instantly: this isn't just surprise, but intense shock bordering on panic. That's why the image is easily lifted out of its comic's context and used as a standalone reaction.
Origin
Rage Comics is a genre of simple comics that took shape on English-language imageboards and forums in 2008–2009 and quickly spread to Reddit and sites like FunnyJunk. The characters in these comics were built from a small set of standard faces, each conveying a particular emotion. OMG Rage Face became one of those faces, establishing itself as the go-to expression of sudden surprise.
Exactly who first drew this face, and in which specific comic it appeared, has not been determined. The anonymous nature of the genre, where authorship got lost in reposts, makes it impossible to name an exact date or author. All that's known is that by 2009–2010 the image was already widely used online as a ready-made reaction template.
Usage and typical captions
Most often the face appears with a short caption like "OMG" or "Oh crap." It's placed under screenshots of unexpected news, plot twists in movies and shows, and posts where someone suddenly realizes they've made a mistake. The emotion is so recognizable that a caption is often unnecessary at all: the face alone is enough.
In discussions, the face serves as a quick reaction to an unexpected turn in a conversation or a shocking figure in a piece of text. Sometimes it's used ironically, to show an exaggerated reaction to things that, in truth, don't warrant that much shock. That lets the image drift from its original meaning and become a universal sign of "I'm floored."
Why the meme stuck
The main reason for OMG Rage Face's popularity is how expressive it is with minimal means. A few lines convey several emotions at once, and the face is easy to recognize even when shrunk down. The exaggeration here works in favor of the humor: an expression pushed to its limit looks funny because real people rarely look like that, yet still recognize their own reaction in it.
The meme is also convenient to use because it isn't tied to any specific situation. It can be dropped into any topic, from gaming news to family conversations, and it immediately sets the tone. It's exactly this flexibility that has kept the image alive in internet culture even after the Rage Comics genre itself lost its former popularity.