Some startling, extraordinary event occurs, and a bewildered spectator (archetypally, a lone tramp with a bottle) decides that some consumable he/she is working on is causing hallucinations, and promptly throws it away. They might also take a vow of sobriety out loud (often with one hand raised), or write down a pledge to stop drinking or drugging. If the person realizes their eyes and/or mind is not playing tricks on them, they may either recant or find a loophole in their decision. Contrast I Need a Freaking Drink, where the situation will make someone on screen turn to drinking.