Sunshine

A day without sunshine is like, dark Idiom taken literally literal darkness (absence of light) Without the sun's light, there would be actual darkness. figurative similar to (idiomatic comparison) The phrase 'like' introduces a simile that doesn't actually explain anything; 'dark' is a tautological description. The pun hinges on 'like' shifting from comparative ('similar to') to introducing a bare tautology ('a day without sunshine is dark'), subverting the expected metaphorical payoff of a simile. .