Why do Japanese people use the kanji "草" (grass) to mean laughter?

Hi, I'm a foreigner and recently started browsing some Japanese forums out of curiosity.
One thing that really confuses me is how people use the kanji "草" (which means grass?) to represent laughter.

I saw a bunch of replies that just said "草" or even "wwwww" and someone told me that "草" somehow comes from that?

Can someone explain how this started and why grass is funny?
I'm genuinely curious.
Thanks in advance!

Why do Japanese people use the kanji &quot;草&quot; (grass) to mean laughter? (22)

Why do Japanese people use the kanji "草" (grass) to mean laughter? (22)