Overconsumption of sugary soft drinks is a major contributor to obesity and related health issues, and is hence a big cause of out-of-control health care costs. A moderate tax on sugary soft drinks, and the elimination of the corn subsidies that make high-fructose corn syrup calories so cheap, will steer consumers to healthier alternatives. This is traditionally called a "sin tax".
Similarly, while most Americans agree that marijuana consumption is not desirable, it is very clear that the costs of prohibition greatly outweigh the benefits. Legalizing and taxing marijuana will provide needed revenue for improving our health care system, and at the same time free up law enforcement to focus on more serious problems and relieve some of the strain on our prison system.