Fussin' over Tussin

The husband is standing in the pharmacy aisle of the grocery store holding a bottle of cough medicine in each hand. One is Robitussin, and the other is the store brand equivalent called just plain Tussin.

He says, "Why does this one cost so much more than this one? They're both the same size. The ingredients are the same. Why does this one cost so much more?"

To me, the answer is obvious. I tell him, "It's the adverTussin."