Where could you legally flash your dong - then spend it?

The đồng is the currency of Vietnam.

The đồng has been the currency of Vietnam since May 3, 1978. Issued by the State Bank of Vietnam, it is represented by the symbol "₫". Formerly, it was subdivided into 10 hào, which was further subdivided into 10 xu, neither of which is now used. Since 2012 the use of coins has decreased greatly, and since 2014 coins are generally now not accepted in retail, but will still be accepted in some banks (not all).

The word đồng is from the term đồng tiền ("money"), a loanword from the Chinese tóng qián (Traditional Chinese: 銅錢; Simplified Chinese: 铜钱). The term refers to Chinese bronze coins used as currency during the dynastic periods of China and Vietnam.

In 1946, the Viet Minh government (later to become the government of North Vietnam) introduced its own currency, the đồng, to replace the French Indochinese piaster. Notes dually denominated in piastres and đồng were issued in 1953 for the State of Vietnam, which evolved into South Vietnam in 1954. On September 22, 1975, after the fall of Saigon, the currency in South Vietnam was changed to a "liberation đong" worth 500 old Southern đồng.

After Vietnam was reunified, the đồng was also unified, on May 3, 1978. One new đồng equalled one Northern đồng or 0.8 Southern "liberation" đồng. On September 14, 1985, the đồng was revalued, with the new đồng worth 10 old đồng. This started a cycle of chronic inflation that continued through much of the early 1990s.