well for starters its not a meme really, a mainstream one at all.
The mask is based off of guy fawks . Google him, I wish to make this short and easy. It made its appearance in V for Vendetta. A character who they never tell his true identity goes by the name V. Watch the movie, read the graphic novel or both its great. V wished to restore power to is people and take down his corrupt government.
Anon on several occasions of internet history did tons of cool justice like stuff. Such as when megaupload was taken down anon (who can be anyone if you somehow don't get it ) hacked and took down I believe 5 government sites as a sign that our governments action in affiliation with sopa, pipa, picpa will not go without action. Such a V would handle it.

You might come across EFG a.k.a EpicFailGuy, who sports a guy Fawkes mask but he fails, if he tries to roll dubs he won't get it, he just fails.
EFG can sometimes win but EFG will always be EFG

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G­ay F­ag anon