The Evolution of "Keep Calm and Carry On"
Believe it or not, "Keep Calm and Carry On was a poster produced by the British government in 1939 during the beginning of World War II, to raise the morale of the British public in the case of invasion. It was little known and never used." (via Wikipedia). However, since it's rediscovery, it has taken on many additional and new faces thanks to distribution mediums like Etsy (for prints). And i'm not one to lie - I have a pink "Keep Calm" (Original) poster framed in my apartment.
If you're looking for a store to purchase these prints, check out KeepCalmStore on Etsy.
To showcase how far this has gone, the following has been created (there are some hilarious ones in here actually)...
full res of graphic available here