Because D.W. uses aliases when discussing her wedding plans with Muffy, the other characters assume that "Dee Woo" and "King James" are adults and set up an official wedding for the two of them. This means that if D.W. and James had said "I do" at the wedding party, the marriage would have become legally binding. If D.W. had never discovered what a wedding actually entails before she went through with it, Elwood City might have been dealing with its first case of child marriage!
How come D.W. doesn't fully understand what a wedding is (she initially thinks it's just a fancy party and doesn't realize it means actually marrying another person), even though she already attended one in "D.W. Thinks Big" and saw her aunt get married? D.W. references the events of "D.W. Thinks Big" in this episode, so it's not a case of Out of Order, either.
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