It’s difficult coming up with a Keep Calm poster which hasn’t already been imagined. As it is, you won’t ever know if you’ve succeeded because it’s theoretically possible somebody may be churning these out for private amusement but not uploading them, making it impossible to ever rest easy.
Here are my contributions. The first is for damsels in distress, the second is NSFW (especially if you work on Wall Street) or at least delicate sensibilities, the third is dedicated to the NRA, and the last is for Sopranos fans:
or how about
Keep Calm It’s Not a Black Hoooooooooooo
as long as we’re on the subject Keep Calm It’s Only Entropy
Keep Calm Haiku is Never The Answer
Keep Calm, i Before e Except After c (not always)
Keep Calm and Pay Your BBC Licence Fee
Keep Calm and Sacrifice Your Son, Abraham
Just because one generation has been hollowly memed out doesn’t mean the next generation, which should be along any minute now, can’t carry on.