A "mnemonics" (i.e. memory) book, published in the late 70's cited this piece. They claimed that it was used as a portion of an "aptitude" test for radio announcers. One line is read and the "testee" repeats it back, the second line is read and the "testee" repeats back both lines, a third line is read and the "testee" repeats back all three lines...etc.

Actually, it is a fun game. Try it.