Someone who uses
internet meme in everyday life around normal people. This can be drawing memes and letting them be seen publicly, using them when talking on Facebook, Twitter etc., saying them in normal
conversation.
They often think they're funnier when people are unaware of what they're talking about. Memefags are most commonly
socially awkward people or early teens kids.
Though not everyone who knows memes, use them like this. People who are familiar with meme but only use them in places where it's acceptable, when seeing someone using memes in a normal real life place, can often start raging.