Warheads, yes teh most sour candy of all.
Lemons? Hell, I eat those whenever I get the chance. Tehy're not sour!
One of my friends had some

that's like cool-aid, except sweeter, and thought it was
soooo sour.. I just put like a large spoonful in my mouth, and it was about as sour as... I dunno, it really wasn't sour at all...
Although, there is this one stuff, it's not candy, and it's not too sour, but it's oh-so yummy!
Citric Acid in powder form... it's YUMMY!