You can probably get away with drinking recently expired pop from a glass bottle, but not from a plastic bottle—and never from a can. Chemicals like bisphenol A will leach from plastic over time into the liquid contents of plastic bottles, and some of these chemicals are both toxic and highly carcinogenic. Cans are even worse, since aluminum will begin to leach into your drink, and aluminum is not only a neurotoxin, but has been linked to Alzeimer’s disease. If you’re buying a drink made outside North America, you should feel the outside of the can for seams; some countries still permit lead solder in the manufacture of cans, and if there’s a seam, there’s a possibility you could be drinking something laden with high levels of lead. Certainly an expired drink can with a seam should never be consumed unless you’re a big fan of brain damage.
By the way, if you’d like to drink something much safer—and tastier—than pop, what I drink is two litres of tap water mixed with about 100 ml of lemon juice, 5 eyedropperfuls of stevia concentrate, and a few drops of flavourings which I alternate depending on my mood, including star anise concentrate, banana concentrate, cinnamon oil, and (real) vanilla. Stevia, if you’re unfamiliar with it, is an herb which has been used for centuries in South America which is 400 to 600 times sweeter than sugar by volume, contains no calories, and has no side effects at all. My concoction has negligible calories, is absolutely delicious, and costs pennies a glass. If you have children, they’ll love it.