A few months ago, my church was hosting a big youth event. After the service a lot of people normally hang around. We decided to sell pizza and pop afterwards as there would be many hungry teens. Pizza + caffeine = party

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In either case, I decided to go loiter by the caffeine which was being sold by Bethany and Sarah (there, you happy, you're famous). I saw Cathi buy a pop and she started tapping it. That got me thinking, does tapping a pop can actually prevent it from foaming upon opening? Time for a science experiment.
Claim: Supposedly if you have a pop can that has been shaken up, and if you tap the top of the pop can, it will prevent the carbonated drink from foaming when you open it.
Hypothesis: The claim is an urban legend, and the pop doesn't foam when you open it because by tapping it, you're giving the pop time to settle back down, and therefore it will not foam.
Lab Equipment: Two cans of 355mL pop. Two witnesses. Two can assistants. Safety goggles, er, my glasses.
Claim Test Case: So we began our experiment. We had Sarah rigorously shake a can of pop, and Cathi tapped the can for about 15 seconds. She nervously opened the can of pop, and it did not foam.
Hypothesis Test Case: I took a can of Orange Crush and began shaking it rigorously as well. After which, I put it down on the table and waited for 15 seconds. I opened it, and sure enough it did not foam.
Potential Errors: As with any good scientific experiment, we should discuss the possible errors that could affect the results. One source of error could be that we used different types of pop in our experiment. Perhaps certain brands of pop are indeed affected by tapping? j/k. Another source of error was that we did not precisely time the duration of the can tapping or the waiting, which could affect our results.
Conclusion: The tapping of the pop can is an urban legend. Tapping the can does nothing. Instead, it is the time you wait before opening the can that prevents it from foaming. To validate the scientific integrity of this experiment, I have searched for sites that have reproduced this experiment, and I found that
Snopes.com had tried the same thing. They conclude that this is an urban legend as well.
Well, that's another useless fact, and time well wasted.