A friend of mine received a letter from a friend of his(creative) who put "Confidential Herpes Test Results" and had a yes or no box on the outside (where 'yes' was checked). This was a brown envelope and professionally done too. LMAO!
A friend of mine broke up with an ad agency art director chick who concocted all manner of such letters and packages. He lived in one of those apartments where the concierge holds your mail and it cost him no end of grief in the building.