See also: Your mom is a horcrux

This is really random, but I desperately need something to explain this to me:



I keep seeing signs like this around. Not Kirkish, but with the "Keep Calm and [do somethingsomething]" crap. There's about a trillion icons with variations of it and there's a store downtown that sells...I dunno, placards of it.

WHAT IS IT FROM? WHAT DOES IT MEAN?

Someone please help me with this mystery.