The folks at MacMerc have posted a way to guarantee that each bottle of Pepsi you buy will get you a free song. Is it a winning code generator? A secret marking on the bottle that indicates if the bottle is a winner or not? A handheld X-ray machine? Nope, you simply tip the bottle until you can read part of the inside of the cap. From MacMerc:

The secret is the angle. Iive found it to be 25 degrees, but thatis really no use when youire out in the field. Just tilt it until it seems about that, and look up towards it (hold it above your head). With luck, you should be able to see under the cap.

[...]

Itis easiest to read "again" and tag the losers because there are no random letters involved. You can spot a word like again from a mile away. If you donit see again and you have given the bottle a twist (to check from all angles), make a purchase. If not, hit the shelf.

You might find it easiest to practice while not in the store. Just buy a few and take them home. Get the knack for the angle, and it isnit that hard to pull off without looking like a huge tool.

You can get more information, along with images and charts, at MacMercis Web site. This has also been mentioned at Slashdot, as well as on the Screen Savers television program.