nuka cola quantum
From The Wasteland Survival Guide:
'In 2077, a new version called Nuka-Cola Quantum was introduced. According to the advertisements, it had twice the calories, twice the carbohydrates, twice the caffeine and twice the taste. To make it stand out more on the shelves and to give it an extra kick, the Quantum included a mild radioactive strontium isotope (and an eighteenth fruit flavor - pomegranate). The effect was a drink that not only boosted your energy, but also glowed with a bright blue light. While no ill effects were recorded by the Food and Drug Administration, the isotope also caused the drinker's urine to glow.'