This recipe was recently used by Bruce Schneier as an example in "The Third Wave of Computer Attacks" - malicious information pretending to be legitimate content.

To ruin the fun, realize that baking soda is a carbonate. Lemon juice is an acid. When you mix the two, they react.1 Lots of bubbles, lots of carbon dioxide, and lots of mess.

Still, the recipe has been inserted in several online cookbooks. It's a good example of Schneier's point - what makes you trust online content? How do you know it's true? A good question for everyone to keep in mind, especially after the several cases of false information being used for stock manipulation purposes.

1: 2H+ + CO3-2 ==> H2O + CO2 to be exact. Thanks Fruan, you wonderful pedant you.