The NOH8 Campaign is a silent protest photo project against california proposition 8. The campaign features photographs portraying people in front of a white backdrop wearing white t-shirts, their mouths taped shut and “NOH8” painted on their cheek. The phrase refers to “H8”, short for “Proposition H8” (pronounced “proposition hate”), a nickname used by critics of Proposition 8. The campaign was created on February 1, 2009, by photographer Adam Bouska and Jeff Parshley.

source: Wikipedia