Scream was made in 1996 by Wes Craven.
The lecture that accompanied the film talked about how is art supposed to be original, when everything has been done before. So the only alternative is to adapt whats already been done.
Scream is a film that takes advantage of the audiences knowledge of typical horror films. That is what makes it humorous in places. It is post modern because the idea of the film is nothing new, but it does play on the fact that you know exactly what to expect.
There is a formula for these teenage horror films. Scream relies on the fact that you know this formula. And we know what to expect because of this formula. For that added extra irony, the characters also know what to expect.