Who wouldn’t want to sound fluent in a second or third language?

Like many learners, I picked up a lot of slang from dramas, but I also learned plenty from my Japanese friends (tomodachi). Of course, I sometimes use it in the wrong context—haha! Being married into a Japanese family has also helped since I get to hear a lot of their casual speech (tameguchi). However, one funny thing is that I sometimes end up sounding boyish with the slang I use. When I get it wrong, people around me laugh, making it even more obvious that I’m not a native speaker.

This got me thinking—when we learn a new language, we often want to pick up slang, but we’re also curious about swear words. No matter how many languages I speak, nothing beats swearing in my mother tongue, Albanian!

But Japanese swear words and slang seem to work very differently. When I asked my family and friends about it, I quickly realized that most Japanese people almost never swear in daily life. Finding information on this topic wasn’t easy—though anime and dramas sometimes feature strong language, I’ve rarely heard people use it in real conversations. Since this isn’t something you’d learn in a Japanese language school, I thought, why not explore and share some insights here?

Bad Mouthing and Dirty Words (悪口・汚い言葉 / Warukuchi・Kitanai Kotoba are organized by category:

• Stupidity

• Body Parts

• Discriminatory Words

Rather than covering every category in detail, I’ll focus on words related to stupidity—a topic that anime, game, and drama fans might already be familiar with!

Common Words for "Stupid"

One of the simplest and most well-known ways to say "stupid" in Japanese is baka (バカ ). But to my surprise, baka has many different usages! Another word with the same meaning is aho (アホ). Why does Japanese have two words for "stupid"?

The reason lies in regional dialects—baka is more commonly used in the Kanto region (Tokyo and surrounding areas), while aho is the preferred term in Kansai (think Osaka).

Both words originally came from Ancient Chinese, with their etymology tracing back centuries. But they aren’t the only ways to call someone foolish! Here are some more variations which I put on a table below:

But wait, there are more Ways to Say "Stupid":

• Saitei (最低) – Literally means "the lowest," but saitei no yatsu (最低のやつ) can mean "asshole" or "jerk."

• Teino (帝の) – Used to describe a dimwit or fool.

• Manuke (間抜け) – A term for someone lacking common sense. The kanji 間 (ma) means "gap" or "space," while 抜け (nuke) means "to lack," so together, it implies someone who is clueless.

• Tonma (頓馬) – Means "stupid jerk."

• Noroma (のろま) – Derived from noroi (鈍い), meaning "slow" or "dull," this word is used for someone who is extremely slow-witted.

• Bonkura (ぼんくら) – A slang term often used by yakuza, meaning "blockhead." It comes from bon (盆), which refers to a gambling tray, and kura (暗い), meaning "dark." It originally described someone bad at gambling or playing games, but it now generally refers to a useless person.

References

• Book: Using Japanese Slang: This Japanese Phrasebook, Dictionary, and Language by Anne Kasschau & Susumu Eguchi

• Research Paper: Japanese Slang on The Nihongo Mantappu YouTube Channel (Morphosemantic Study) by Nastasya Kirana Dewi & Raden Novitasari

• Preply: Japanese Slang

• Flip Japan Guide: Japanese Slang