Ewwww. Just ewwww.
Soured up lemonade with sweetener would probably be great. (I'm switching from sucralose to stevia so I'd have to add my own sweetener but when I run out of my current bottle of lemonade I might try that.)
Poeia, you'll notice that stevia is incredibly more sweet than sucralose (if you haven't already) and in some instances actually can be so sweet that its sour. it'll react differently with different flavors too. good change to make!!!