kusa 草 - Meaning in Japanese | Japanese with Anime

In Japanese, kusa 草 means "grass" or "weed," but it's also a Japanese internet slang for "lol," used when you're laughing at something, at someone's joke, for example, or at someone doing something stupid, and so on.

Anime: Uncle from Another World, Isekai Ojisan 異世界おじさん (Episode 1)

Origin

The reason why kusa 草 means "lol" is because of another internet slang: wwww at the end of phrases, which also means "lol," or bursting out laughing. In manga and anime, typically this would show up used by trolls mocking people for all sorts of things

Context: someone is weak, trolls troll:
yowa wwww
弱ｗｗｗｗ
[Wow, he] is [so] weak, lolololololol.

These w's placed horizontally side by side take a form that resembles grass blades, so kusa is a sort of visual pun on that.^{(コトワカ:「草生える」とは？)}

Source: japanesewithanime.com (CC BY-SA 4.0)

草が生える

Some ways kusa is used:

yowa-sugite kusa ga haeru
弱すぎて草が生える
Because [he] is so weak, grass grows. (literally.)
Because [he] is so weak, wwww.
Because [he] is so weak, I laugh.
lol [he] is so weak.
yowa-sugite kusa-haeru
弱すぎて草生える
(same meaning.)
yowa-sugite kusa
弱すぎて草
(also same meaning.)
yowa-sugite kusa w
弱すぎて草ｗ
(same meaning, too.)

The pattern above is the te-form of a predicate (above, a verb) followed by kusa ga haeru. For an i-adjective that would be ~kute ～くて, while for other adjective types it would be de で.

baka de kusa w
馬鹿で草ｗ
lol [he] is stupid.

Anime: Uncle from Another World, Isekai Ojisan 異世界おじさん (Episode 1)

Context: an uncle from another world reads comments on his Youtube video.
Takeshi
たけし
(username, male given name.)
kusa-haeru wwwww
草生えるｗｗｗｗｗ
Grass grows wwwww.
Ohimesama
お姫様
Princess.
(username.)
ojisan kao makka
おじさん顔真っ赤
[Old man]''s face is red.

草原

The word sougen 草原 means a "grassy field," since laughs in internet comments look like grass, a "grassy field" may refer to there being a lot of laughs.^{(日本語表現辞典:大草原不可避)}

大草原

The word daisougen 大草原 means literally "great grassy field," which in internet slang would mean there's a lot of people laughing at something or someone.

That would be great, right? Everyone having fun. Except these "laughs" are typically not "laughing with you," they are "laughing at you," so there being a daisougen means you did something so stupid that commenters on your post or online stream are all laughing.

daisougen wo tsukuru
大草原を作る
To build a great grassy field. (literally.)
To do something so ridiculous it gets in response a bunch of laughs.
daisougen fukahi
大草原不可避
Great grassy field inevitable.
Used to say doing something will inevitably lead to a reaction where everyone will be laughing.

It may be worth noting that in mahjong, 麻雀, a board game popular in Japan, of which some series are even about, there's a different but similar-sounding term: daisangen 大三元. This refers to forming a hand containing one triplet of every one of the three different dragon tiles (white tiles, red dragons (中), and green dragons (発)). For context, there's only 4 tiles of each in a game, so it's very unlikely for someone to end up with a hand containing 3 of each. The daisangen is a yakuman 役満 hand, meaning it awards the maximum points possible for a single hand. There's also a yakuman that contains only green tiles, called ryuuiisou 緑一色. Either of these could be the source of some pun involving the green grassy laughs.