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I've never encountered these at all. A strange and somewhat interesting thing.
I wish more folklorists studied internet memes. Because the web is such a good little Petri dish to understanding exactly how cultural memes develop. We wonder how we got pantheons of gods and epic mythology cycles and superstitions, well, this is it.
I've seen a couple of these around, but not much and had no idea they were a 'thing'. Perhaps they are a thing on Reddit only and this is someone's attempt to force a meme? If so (and I'm only guessing, of course), it won't work, because memes can't be artificially created I don't think. They have to grow organically.
These faces are common usage in Reddit and several of the chans. They're a useful shorthand for reactions, like emoticons with enough depth to stand in for characters in a story.