Provenance — where it came from
Japanese internet users used to write laughter with the kanji 笑 (warai, “laugh”) at the end of a sentence. But typing the kanji takes time. On message boards and in online games, people shortened it to its first roman letter: a single w.
One w is a small laugh. Funnier things earned more: wwwww. Then, at some point, someone looked at a row of w’s and saw something else — blades of grass. So laughter became 草, “grass.” “Grass grows” (草生える) now means that made me laugh. And for something extremely funny, the grass becomes a whole field: 大草原 — “a vast prairie.”
It started as a lazy shortcut. In the 2010s, it moved from anonymous forums into everyday text messages, and became one of the most common words on the Japanese internet.
Field notes — how it’s used
朝起きたら猫が財布の上で寝てた。草
asa okitara neko ga saifu no ue de neteta. kusa
“Woke up and the cat was sleeping on my wallet. lol”