Please note: If you didn't succeed before, try again!
They extended the deadline to 6 pm EST Monday November 24, so I decided to try registering again. However, this time, the site told me that the email address I entered was already in use. So, possibly one of my earlier attempts to register was actually successful.
ETA: It suddenly occurred to me that I ddn't finish the coupon request process. I went back to the site and logged in, and succeeded. I was then able to complete the steps to request the coupon. So it looks like I'm getting a free Dr. Pepper after all.
You are absolutely right about that. I've won lots of stuff in the past that came in the mail looking like junk and if I hadn't been in an "oh well, what the heck, I'll open it anyway" kinda mood I never would have even gotten my prize. It would be interesting to see the stats... how many prizes are won versus actually claimed. At any rate, just wanted to let folks know that these are coming 'disguised' so don't throw them away!