How is Spam made? The butt of countless "mystery meat" jokes, the basic ingredients of Spam aren't all that mysterious: pig shoulder and rear, along with spices, salt and sodium nitrite. What remains a closely guarded secret is the technological side of production, which involves a combination of "vacuum mixing, quick sealing, and pressure cooking," resulting in a jiggly block covered in gelatinous muck that, when sliced, resembles giant pink erasers.