What is Children Of Lieutenant Schmidt?

Legal Definition
Children of Lieutenant Schmidt (Russian: Дети лейтенанта Шмидта) is a fictional society of swindlers which appeared in the 1931 satirical novel The Little Golden Calf by Ilf and Petrov. They pose as children of Lieutenant Schmidt, a hero of the Russian Revolution of 1905. The main antihero of the novel, Ostap Bender, befriends two hapless members of this society.

The novel is set in Russia in the 1920s, and its premise is that at the time, numerous fake relatives of Karl Marx, Prince Kropotkin, and other revolutionary figures roam the country, tricking gullible Soviet officials into giving them money. Their numbers grow, and to prevent any unlucky chance of spoiling each other's attempts, they "unionize", with Schmidt's Children being the most difficult to organize. When the latter finally convene, "it turned out that Lieutenant Schmidt had thirty sons, from eighteen to fifty-two years in age, and four daughters, unattractive, and no longer young." They split Russia into 34 territories.

Ostap Bender, being in difficult straits, decides to play the same game, but runs into another trickster (Shura Balaganov, who becomes his accomplice) right in front of a bureaucrat in a Soviet office. Bender manages to get out of the gaffe by pretending Shura is his brother. Later they meet yet another "sibling" - Mikhail Panikovsky (Russian: Михаил Самуэлевич Паниковский), who is running for his life (he had ignored the convention, trespassed, and was caught red-handed by victims of yet another "brother").
-- Wikipedia