mack
n.— «Mr. Levine and his client were prisoners in California’s Lompoc Federal Correctional Complex. Like other federal inmates around the country, they found a can of mackerel—the “mack” in prison lingo—was the standard currency.» —“Mackerel Economics in Prison Leads to Appreciation for Oily Fillets” by Justin Scheck Wall Street Journal Oct. 2, 2008. (source: Double-Tongued Dictionary)
Further reading
In 1971, when a new public library opened in Troy, Michigan, famous authors and artists were invited to write letters to the city’s youngest readers, extolling the many benefits of libraries. One of the loveliest was from E.B. White, author of...
Cat hair may be something you brush off, but cat hair is also a slang term that means “money.” In the same way, cat beer isn’t alcoholic — some people use cat beer as a joking term for “milk.” And imagine walking on a...