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.