Electronic dictionary commercial

A commercial I saw recently for an electronic dictionary prominently featured only one English word, and that word wasn't even incorrect, but it still leaves me wanting to correct the commercial.

The commercial shows a student studying English. He has made a bunch of flashcards--they are actually stickies with a word written in Chinese and in English on them. One of the notes gets stuck on his forehead. It says "stupid" in English, and in larger writing it says "bendan" (笨蛋) in Chinese.

The problem is that bendan means "fool" or "idiot," but the word "stupid" is only rarely used in this sense in English (as in "Keep it simple, stupid"). Some dictionaries don't even list this noun form of "stupid." So, while the flashcard is not technically wrong, I find it hard to believe
that a student would need to make a flashcard for this infrequent use of the word.

"Idiot" or "fool" would have been a much better choice for the English "translation"; alternatively, the Chinese word could have been changed to the adjective form (笨). As it stands, it will cause viewers to think that "stupid" and "bendan" are equivalent. But they aren't equivalent and you can't, for example, say "He is a stupid."

Links:

Commercial on official site.
Commercial on Youtube.