A keystone is the stone at the apex of an arch. The arch can not stand without it. If the keystone is removed, the entire structure collapses. Although you would think it experiences a great deal of force, it actually experiences little to none, and is often the most fragile as a result. I think it's the kids.
You can't be this dumb. It's Stephen by the way. Yo, Steve, CIA/MEU = psyop, right? Is the 'harassment' stuff part of a package to prepare Americans for the really bad stuff?