Kusa-fu-eru (草生える) is a piece of Japanese internet slang used to signify laughter. Literally translating to ‘grass grows,’ it stems from the common practice of using the letter ‘w’ to represent laughter—resembling a laughing face or a series of smiles. Because a long string of ‘w’s looks like blades of grass, Japanese users say ‘the grass is growing’ (kusa ga haeru) when they see something extremely funny.
In Japanese online culture, the character ‘w’ is derived from the kanji ‘warau’ (笑), meaning ‘to laugh.’ When a user finds a post hilarious, they might reply with ‘wwwwww.’ Visually, this string of characters resembles grass on a field, leading to the slang term kusa-fu-eru. Often, users will simply write ‘kusa’ (grass) as a shorthand for ‘lol’ or ‘lmao.’
How to Use Kusa-fu-eru
You will mostly encounter this on platforms like X (formerly Twitter), LINE, or video comment sections. It is strictly informal.
User A: Did you see that funny video of the cat?
User B: Yes! Kusa. I couldn’t stop laughing.
Pro-tip: Be careful where you use this! Because it is strictly digital slang, never use ‘kusa’ or ‘kusa-fu-eru’ in formal business emails or face-to-face conversations with superiors. Stick to polite Japanese in those scenarios.
If you enjoy learning about how digital culture shapes language, check out our guides on other informal expressions: What Does ‘Yaba-tan’ Mean? and What Does ‘Ikeru’ Mean?
