The now-famous Keep Calm and Carry On poster was produced by the British Ministry of Information in 1939, as a quintessentially British statement of what to do in the event of German invasion. The poster actually wasn't circulated at the time, and only became popular after its rediscovery at a bookstore. Among my friends, it's something of a mantra -- I know one woman who has the phrase sewn into the lining of her coat.
But enough with boring history. Let's look at some wacky variations on the poster that have appeared online. Tip for nerds: a lot of these are available as prints (and notebooks, phone covers, mouse pads, you name it) from various online vendors. Google it.
1. Keep Calm and Call Batman
I first saw this on a whiteboard at a software company. Get Commissioner Gordon on the phone!
2. Don't Panic and Carry a Towel
For all the hoopy froods in the house.
3. Keep Calm and Kill It With Fire
Everyone knows The Thing can only be killed with fire. Also: winter is coming.
4. Keep Calm and Save the Princess
Mario or Zelda? You decide.
5. Freak Out and Call Mom
She'll want to hear what's up.
6. Stress Out and Throw Vase
This is what you do if Mom isn't picking up.
7. Keep Calm and Have a Cuppa
A spot of tea always helps.
8. Keep Calm and Aim for the Head
Necessary advice for the coming zombie apocalypse.
9. Keep Calm and Harry On
Useful while you're waiting for that damn Sorting Hat to figure you out.
10. Keep Calm and Simply Walk Into Mordor
Easy for you to say, Gandalf!
11. Run Out of Ideas and Make a Parody
Oh, internet. How self-aware you've become!
There are zillions more in a Flickr pool devoted to this sort of thing.