An image with a long, murky history with 4chan and Something Awful. Popular with probably every board, including /tg/. In its primordial roots, it was created on a now-defunct Pokemon fansite (Pokemopolis) of all places, where it was known as the :cheesy: smiley. The creator also posted in on Something Awful, where the Goons made it into what it is now.
If someone replies to your post with this image attached, he is essentially saying something along the lines of "fuck you" or "you're a fucking retard". This person is probably correct, since the purpose of /tg/ is /to generate/ RAGE.
Vecna is the primary example of awesome in D&D, since he's the Batman wizard who broke the game so hard in 2nd edition, that he caused the edition change to 3rd. He avoids Mary Suedom primarily by being awesome, and by ultimately losing, though he had a partial success since he ultimately went from demigod to lesser god.
In fantasy, the biggest example of awesome is FUCKING NORSCA. BECAUSE VIKINGS.
If you play 40K, draw this face on your blast templates for lulz.
In battletech there is an mech named Awesome, it is indeed pretty awesome.