Hi Kimberly -
The rule is that if it's not on the list of 100 permitted foods, you are not suppoed to have it.
I'm not saying you can't lose weight if you have it, I do know some people who tweak a bit and are still happy with the way the plan is going for them. I would personally say that if you aren't having a huge amount of it (say no more than a couple of coffees a day) and that would be the difference between staying on the plan and not staying on plan, then just give it a try.
There aren't too many Dukaners posting on 3FC but a few of us are here