Nothingness.org has an excellent collection of the posters which appeared around France in May 1968. The poster above depicts the police--les frics--as the enemy.
Elsewhere, you can also look at graffiti from the same era. This post's title is but one of many from the walls outside the University of Nanterre in France in May 1968. I also like the one that says "I'm a Groucho Marxist."