草
くさ
kusa
= internet slang for “lol” / uncontrollable laughter (from 笑 → w → 草)
Kusa literally means “grass,” but if you see it under a Japanese tweet or stream clip, nobody is talking about lawns. It means “lol,” and the reason a plant became a laugh track is one of the more delightful accidents in Japanese internet history.
The chain starts with the verb warau (to laugh), which got abbreviated in early online chat to just the letter “w.” Typing multiple w’s for extra-hard laughter — “wwww” — became common, and someone noticed that a row of w’s on screen resembles blades of grass sprouting from the ground. From there, users started writing 草 (“grass”) instead of the w’s themselves, and eventually 草 became a standalone word for “that’s hilarious.” The intensity scales with the imagery: a lot of laughter is daisougen (“a huge grass field” / “a whole meadow”), and something laugh-out-loud funny gets tagged kusa haeru (“grass is growing”) or kusa fukahi (“grass is unavoidable”). You’ll see it dropped alone as a one-word reaction, stacked as 草草草 for emphasis, or worked into a sentence as a genuine noun, as in sore wa kusa (“that’s grass,” i.e. “that’s too funny”).
草 lives almost entirely in typed, informal contexts — comment sections, group chats, stream and video comments, social media replies. It is not something you’d say out loud in conversation; there’s no spoken equivalent, since the whole joke depends on how the text looks on screen. Compare it to plain 笑 (warai) or (笑), which read as a mild, slightly old-fashioned “(laugh)” tacked onto a sentence — 草 is louder, more current, and skews younger. A common trap for learners: because 草 grammatically functions as a noun, it can follow particles like a normal noun (sore, kusa da wa), which feels strange until you accept that Japanese net culture treats “grass” as a genuine reaction word, not just an interjection.
Everyday use
え、それマジ草なんだけど
E, sore maji kusa nan da kedo
Wait, that’s seriously hilarious
Casual / Social Media
配信でのその失敗、大草原不可避www
Haishin de no sono shippai, daisougen fukahi www
That fail during the livestream — impossible not to burst out laughing
Formal / Cultural context
ビジネスメールで「草」と書くのは避けて、「面白いですね」と書きましょう。
Bijinesu meeru de “kusa” to kaku no wa sakete, “omoshiroi desu ne” to kakimashou.
In business emails, avoid writing kusa; use omoshiroi desu ne (that’s amusing) instead.
草’s rise tracks the growth of Japan’s early web forums and video platforms. The “w for warau” habit took hold on bulletin boards like 2channel in the 2000s, where brevity mattered and stacking letters was faster than typing out a full reaction. Niconico Douga, the video site famous for comments that scroll directly across the screen, then supercharged the trend: when dozens of viewers typed “wwww” over the same funny moment, the screen genuinely filled with rows of w-shapes, and “it looks like a field of grass” became a running joke that stuck as an actual word.
Part of why this kind of visual pun thrives in Japanese specifically is the writing system itself. With three scripts in play — kanji, hiragana, and katakana — plus a long history of wordplay built on how characters look and sound, swapping an alphabet letter for a kanji that resembles it fits naturally into existing habits of Japanese internet humor. 草 has since spread well beyond its origin sites into mainstream texting and social media, though it remains a marker of casual, extremely online speech rather than something that belongs in polite or professional writing.