Japanese internet slang for laughter, functioning like a visible laugh — you say it when something's funny, escalate it when it's hilarious.
草 (kusa) is how Japanese internet users signal laughter in text — the digital equivalent of laughing out loud at something genuinely funny. It appears as a standalone comment or tacked onto the end of a sentence, functioning less like a word and more like a visible laugh. When something's funny, you drop a 草. When it's hilarious, you escalate: 竹 (bamboo), 森 (forest), 大草原 (great plains), even アマゾン (Amazon). The botanical metaphor stretches as far as the laughter demands.
The term emerged on 2channel imageboards in the mid-2000s from pure visual accident. Users typing 'w' repeatedly to indicate laughter — drawn from 笑う (warau, 'to laugh') — created patterns that looked like grass growing: wwwww. Someone noticed, started using the kanji for grass instead, and it spread. By the mid-2010s, smartphones made typing 草 faster than multiple w's through predictive text, turning a clever metaphor into practical efficiency. In 2018, it entered Japan's national dictionary.
草 reveals something about Japanese internet culture's relationship with language: playful, visually creative, willing to let accidents become systems. It's the kind of slang that emerges when communities value linguistic innovation as much as the joke itself.