Etaoin Shrdlu – pronounced “eh-tay-oh-in shird-loo” – is a sounding out of the twelve most common letters in English, in order of frequency of use. The expression goes back to the days of linotype typesetting machines. (As an aside, if your unfamiliar with the details of this fantastic gizmo, spare a moment for the wiki entry… the thing’s an engineering marvel, and the lingo that sprouted out around it’s operation is wonderfully quirky) According to the internets “Were one to run a finger down the first and then second left-hand vertical banks of six keys on a linotype machine, it would produce the words etaoin shrdlu. Linotype machines were sometimes tested in this manner. Once in a while, a careless linotype machine operator would fail to throw his test lines away, and that phrase would mysteriously show up in published material. The full sequence is etaoin shrdlu cmfgyp wbvkxj qz.” Now you know, in case it comes up.