In Neal Stephenson's book Cryptonomicon, there is a reference to a military manual titled "Tactical Negro Impersonation Volume III: Negroes of the Caribbean". It gives advice on how a ship's crew should behave to fool passing submarines into thinking that their ship is crewed by dark-skinned natives and not white US Navy personnel.

I don't know if this book actually existed, or if it was something Neal made up when writing his novel. The fact that I can't find any reference to this on the Internet (other than a few links on E2) indicates it is probably fictitious -- or classified.