The Aku FOOL meme originates from the Cartoon Network series Samurai Jack. Notably, the context is when, in a given episode, Samurai Jack appears to have triumphed over insurmountable odds against the machinations of Aku and comes with in the proverbial arm's reach of his ultimate goal of going back in time, only for the Master of Darkness himself to come in at the last moment to snatch his prize/victory away, yelling "FOOLISH SAMURAI!" or simply "FOOL!" at the hero.

This now becomes a meme representing a long-standing goal, any goal, and/or moment of success, almost being achieved but then falling short of the expected triumph due to some unknown but overwhelming last-minute hindrance. The cause of the hindrance is not immediately obvious, leaving the laborer of the goal in the dark as to what went horribly wrong, thus Aku becomes the personification of this 'unknown' factor. In a strip, this meme will often be immediately followed by a Rage meme.