Denny's are a little sparse out here, so I don't know if I will be taking them up on that or not. (If I was still in SoCal, I could have hit three of them WALKING...well...let's say "bicycling" instead)
I immediately went to Dennys.com after the first commercial, and ... it was down. Once I got through, I found out the closest Denny's is 37 miles away. 75 miles worth of gas is about a wash to get a free breakfast that sells for $5.99. Add in the opportunity cost of time, and I will not be taking them up on their offer.
And in response to that, I direct you to the two links AWArulz posted, indicating that the only thing the two of them did was take off their first layer of clothing to reveal a *gasp* Forbidden Message.