MacMerc has posted instructions, photos and a diagram on how to “spy” the inside of specially marked bottles of Pepsi, Diet Pepsi and Sierra Mist to make sure it has a winning code. “The secret is the angle.
I’ve found it to be 25 degrees, but that’s really no use when you’re 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.”.