Heroes will every once in a while be offered a drink that they'd rather not partake of. Maybe they don't trust the one who gave it to them. Maybe it looks like an Alien Liquid Lunch or the product of a Lethal Bartender. Maybe they just don't do alcohol, or need to be on the top of their game for an upcoming fight, and can't just say so without giving something away. Whatever the reason, they'll discreetly pour it out or pass it off while no-one's looking. Compare Slipping a Mickey and Discreet Dining Disposal. Overlaps with That Poor Plant when the drink is poured on a potted plant.