The famous “Keep calm and carry on” poster was created in 1939 by the british governent to raise the morale of the people at the beginning of the Second World War. Is curious but, due to poor distribution, the poster had no success. At the beginning of the XXI century, it’s recovered and comes into fashion, causing a large number of interpretations and parodies.
Those are the posters we like the most:
Darma 
How about including an example of the “response” I’ve seen on T-shirts: “NOW PANIC and FREAK OUT”