socks and knocks
n.pl.— «Readers should understand clearly that if the power industry prevails in its court challenges to the initiative, the huge amount of money expected to be spent primarily on reducing what the industry commonly calls “socks and knocks” might not get spent. (“Socks and knocks” is a word play on the symbols for sulfur dioxide and nitrogen oxides, SO2 and NOx, respectively.)» —“Cleaning Up With ‘Socks and Knocks’” by Bill Paul Motley Fool Apr. 21, 2005. (source: Double-Tongued Dictionary)
Further reading
If you speak a second or third language, you may remember the first time you dreamed in that new tongue. But does this milestone mean you’re actually fluent? And a couple’s dispute over the word regret: Say you wish you’d been able...
While reading Great Expectations (Bookshop|Amazon) by Charles Dickens, a listener in Arlington, Texas, is surprised when one of the characters inherits some money, which Dickens describes as a cool four thousand. Were they really using cool that way...