Could one of you scholars please explain the joke for us smoothbrains who don't get it? All I see is a boolean matrix, and I'm not even sure that is correct.
That matrix of zeros with one in diagonal is called the matrix of identity.
It is famous because when doing multiplication on matrix or vector, it acts likes 1 on "normal" number:
x times 1 is x.
anyMatrix times Identity is anyMatrix.
Identity theft is not a joke, Jim. Millions of families suffer every year. Also one that the internet gets wrong all the time: “dude, this is a Wendy’s”, not “sir this is a Wendy’s”