Cure Cancer Day!
Mix a can of Red Bull with a teaspoon of baking soda and some elk pee. Then make a cancer patient drink it, but only if famous doctors are watching because his cancer will be cured so quickly and thoroughly that the doctors might not believe that he ever had cancer unless they saw him before the cure. Red Bull and most baking sodas are already patented, but you might be able to patent elk pee. I'm not sure. Like could I patent kitten spit? I doubt it, and if I could I bet someone already beat me to it.
But you might be able to patent the finished potion. If you can't, then I wouldn't bother telling anyone about the cure because you won't make any money.
Happy Cure Cancer Day!