That's a double two-em-dashed lie, you etaoin shrdlu so-and-so!
1931, journalism slang, the sequence of characters you get if you sweep your finger down the two left-hand columns of Linotype keys, which is what typesetters did when they bungled a line and had to start it over. It was a signal to cut out the sentence, but it nonetheless sometimes slipped past harried compositors and ended up in print.
Confusion; mistakes: 98 percent accurate and 2 percent etaoin shrdlu
[1931+; fr the phrase typeset by sweeping one's finger down the two left-hand columns of Linotype keys, in a gesture made by compositors when they have erred and must begin again]