The Sam Vimes theory of socioeconomic unfairness, often called simply the boots theory, is an economic theory that people in poverty have to buy cheap and subpar products that need to be replaced repeatedly, proving more expensive in the long run than more expensive items. The term was coined by English fantasy writer Sir Terry Pratchett in his 1993 Discworld novel Men at Arms. In the novel, Sam Vimes, the captain of the Ankh-Morpork City Watch, illustrates the concept with the example of boots.

The theory has been cited with regard to analyses of the prices of boots, fuel prices, and economic conditions in the United Kingdom.

Když jsme se blížili k východu, ptal se mě, jestli si jdu koupit lístek.

„Ne, mám tramvajenku.“

„Vážně? Tramvajenku? To jako na celý měsíc?“

„Jo, na celý měsíc,“ zalhala jsem. Nechtěla jsem přiznat, že mám celoroční, protože takový výdaj by Michala asi zaskočil.