There's no problem with ripping off memes (that's part of what memes are for, and that's generally how they're made). Lynch1979's meme itself isn't an original joke either.
But this one goes against submission guidelines, because it's an obvious repost (the other one's still on the front page). He should have made it for use on other sites (maybe the user saw it as an improvement for regions where they spell it "mum" instead of "mom"), but without submitting it. At least, not this soon.
Caption this Meme
