Never put off till tomorrow what you can do the day after tomorrow just as well.

The line is widely attributed to Mark Twain as a characteristically deadpan inversion of the moral maxim “Never put off till tomorrow what you can do today.” It circulates chiefly as a standalone aphorism in quotation collections and popular humor anthologies rather than as a securely traceable sentence from a specific dated speech, letter, or published work. Twain’s public persona and much of his comic writing often relied on parodying earnest Victorian self-improvement advice by pushing it to absurd conclusions; this quip fits that satirical mode, presenting procrastination as if it were a rational efficiency principle.

The sentence parodies the moral pressure to be productive by pushing procrastination to an absurd extreme: if a task can be done “the day after tomorrow just as well,” then even tomorrow is unnecessarily soon. The humor depends on faux-reasonableness—an apparently rational criterion (“just as well”) used to justify delay. Read more broadly, it satirizes the way people rationalize inaction and exposes how easily “practical” reasoning can become self-serving. As with much Twainian wit, the joke also hints at skepticism toward rigid virtue-signaling: the proverb’s moral certainty is replaced by a shrugging pragmatism that reveals human laziness and the elasticity of our excuses.