The Secret History of Typography in the Oxford English Dictionary

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Citing usage from 1949, the OED calls this mark the dog’s bollocks, which it defines as, “typogr. a colon followed by a dash, regarded as forming a shape resembling the male sexual organs.” This is why I love scrounging around the linguistic scrap heap that is the OED. I always come across a little gold. And by “gold,” I mean, “vulgar, 60-year-old emoticons.”

The Secret History of Typography in the Oxford English Dictionary — The Bygone Bureau