From the Lawrence Daily Journal-World for Jan. 28, 1973:

The Pentagon recently had released a pamphlet intended to acclimate returning prisoners of war to the cultural changes that had occurred in the U.S. during the Vietnam war. According to the publication, POWs were expected to be unaware of the moon landing in 1968, Richard Nixon’s election in 1968 and re-election in 1972, or the My Lai massacre. The pamphlets, which were to be distributed to POWs upon their arrival at Clark Field in the Philippines, was “not mandatory reading” and was “just another way to bring them up to date,” a Pentagon spokesman said. In addition to major events, sports highlights, and deaths of prominent individuals, the booklet also covered the topic of current slang. “Hey, big daddy, when your young son or daughter comes to you and says, ‘Do you dig?’ you can say, ‘Lay it on me dude,’ and ‘right on.’… This is a part of the language and the slang being used by the youth of today — your sons and daughters,” the pamphlet advised the soldiers.