It is not clear whether the couple, Tareq and Michaele Salahi, had an invitation to attend the dinner. Considering how elaborate and meticulous such dinners are and the level of planning they require, it is inconceivable that anyone could have bluffed their way into perhaps the world’s most guarded complex.

I'm not going to spend a lot of time on this story because it's pretty obvious what happened. However, in reference to the statement above, I will point out that inconceivability is the most potent weapon used against security. If no one would conceive of attempting a particular form of interference the interference will virtually always work because no one will be actively preventing it ...