Dog tags of the Vietnam war

People in the army wear necklaces with tags that contain their information on it (name, blood type, etc.) which are called dog tags. In this case, the dog tags do not belong to actual dogs, but to the milatary personnel who lost their lives.

Joke: a thing that someone says to cause amusement or laughter.

I had hoped that you were simply ignorant, but turns out that you are only quite rude.