Tapping the Can Does Not Stop Foaming

I am sure many people have seen, or have done it themselves, a person tap a can of soda or beer, before opening it. Hey, I am not going to lie, I have done it myself. We even witnessed this act of tapping a can of soda in the movie,Urban Legends, that we watched in class (the scene with the pop rocks and soda). But supposedly, tapping does almost nothing.
If a can is going to foam up and spill all over, with or with out tapping, it going to do it. Supposedly, the tapping might make it a little better, but that's only because you are giving it more time for the bubbles to "calm down." The best thing to do, is if a can was shaken, is to let it sit for awhile. So, tapping is pretty much a waist of time and energy.