Ben Rich claimed to not stamp “classified” on documents to keep people disinterested.

I don’t remember noticing this before but in Ben Rich’s personal memoir he states…

“In fact, Kelly evolved his own unorthodox security methods, which worked beautifully in the early days of the 1950s. We never stamped a security classification on any paperwork. That way, nobody was curious to read it. We just made damned sure that all sensitive papers stayed inside the Skunk Works.”
― Ben Rich CEO Lockheed Skunk Works

On Google Books: https://books.google.com/books?id=oL4bHPIt7XIC&pg=PT32&lpg=PT32&dq=%E2%80%9CIn+fact,+Kelly+evolved+his+own+unorthodox+security+methods,+which+worked+beautifully+in+the+early+days+of+the+1950s.+We+never+stamped+a+security+classification+on+any+paperwork.+That+way,+nobody+was+curious+to+read+it.+We+just+made+damned+sure+that+all+sensitive+papers+stayed+inside+the+Skunk+Works.%E2%80%9D%0D%0A%E2%80%95+Ben+Rich+CEO+Lockheed+Skunk+Works&source=bl&ots=gfFYHkNfPa&sig=ACfU3U2Nf_RsYKn4Rck42PoiBEUYg8BuIQ&hl=en&sa=X&ved=2ahUKEwiHlubt69CAAxUwlGoFHQe6D8kQ6AF6BAgIEAM#v=onepage&q=%E2%80%9CIn%20fact%2C%20Kelly%20evolved%20his%20own%20unorthodox%20security%20methods%2C%20which%20worked%20beautifully%20in%20the%20early%20days%20of%20the%201950s.%20We%20never%20stamped%20a%20security%20classification%20on%20any%20paperwork.%20That%20way%2C%20nobody%20was%20curious%20to%20read%20it.%20We%20just%20made%20damned%20sure%20that%20all%20sensitive%20papers%20stayed%20inside%20the%20Skunk%20Works.%E2%80%9D%20%20%E2%80%95%20Ben%20Rich%20CEO%20Lockheed%20Skunk%20Works&f=false