Toffee / For toffee

Not to be able to do something 'for toffee', as in ‘he can’t play tennis for toffee’ is a British colloquialism (the OED says slang) for incompetence, and dates from the late 19th century. Quite why toffee was chosen in this context over anything else remains obscure. Toffee is also British slang for rubbish or nonsense, and dates from the 1930s.