How about one more you fool? （ぼけなす）

He Says:
bokenasu　（ぼけなす）=idiot
Boke is fool, nasu is egg plant.
Especially used in Osaka. So they would be insult as fool and egg plant which is hard to understand...it's like a double punch.

She Says:
"You are one stupid eggplant."
"Back off, foolish eggplant!"
"Shut the fuck up you dumb eggplant!"
I think this is a word that definitely loses something in translation. I'm not convinced that any foreigner could pull this one off with the type of intensity needed to properly throw this insult. I mean, you could say it all angry-like...but then wouldn't you start to giggle when you thought about what it meant?

The next word is...へんたい。

Could there be more words for "fool"?(ばか)

He Says:
baka　（ばか）=fool
This means also fool, but it's more polite way to say fool than aho or boke.
Because baka is used by Tokyo people(East Japan), who speak standard and polite Japanese.
And Japanese women tend to use this word to say fool.
So, here is a sign...when a girl says baka quietly to you with smile, she may like you, isn't angry so much, just feels comfortable being with you.

She Says:
Great. Another way to say "fool". I'm not sure why this is such a popular insult in Japan. Again, this is another well known "bad Japanese word", but it's not so bad that you wouldn't hear children say it.
But let me tell you a story about "baka". Long before I met my husband, I went out with this guy a couple of times. He didn't really speak much English and I didn't speak much Japanese. The first time we went out, his friend was there to translate. The second time, the friend wasn't there. I thought I'd give it a try. Bad move. Anyway, we were hanging out with his friends, another couple. Suddenly, completely out of nowhere, the guy I was with started punching the other girl. I mean, really punching her. What the hell, right?
Can you imagine what I wanted to call him and how frustrating it was that "baka" was the only insult word I knew at the time?

The next word will be...ぼけなす.

Another Japanese Fool （ぼけ）

He Says:
boke　（ぼけ）=fool
It's almost same meaning with aho (yesterday's dirty word), but boke is dirtier and more impact word than aho.
So saying only boke is already so powerful to hurt in itself.
Basically, boke means dementia.
Used in mostly west Japan(Osaka,Kyoto,Kobe etc), so it'll more impact to use to Tokyo people(East Japan).

She Says:
Boke is an angry word. You don't really say it in jest. Boke literally means "senility". It can really hurt someone if you say it, so don't say it to the people you love. Again, this ones gets translated as "fool", but I would say that a more accurate translation to English would be like calling someone a "retard".

The next word is...ばか。

A Japanese Fool （あほ）

He Says:
aho　（あほ）=fool
Accent is aho. We can use aho to abuse, run the person down.
Aho is used in mostly west Japan (Osaka,Kyoto,Kobe etc).
So it'll more impact to use to Tokyo people(East Japan).

She Says:
Like He said, aho is used mostly in Western Japan, which makes this term "cooler". Essentially it's an insult, but when said among friends, it's more playful teasing. For example, if someone tripped and fell over their own feet, you might call them an aho. But you might also call the guy who cheated on you an aho. (Note that this is not a very strong/angry word. If you were really angry at someone, you'd use other words. Of course, this all depends on the tone and I think you'll know if someone is angry and calling you an aho vs. when you've done something stupid.) Although it gets translated as "fool", that's not really a word that's normal to use in English...I'd translate it more as "jackass" or "dumbass".

The next word will be...ぼけ。