I came across the term 草生えた on the internet. There wasn't much context, but it didn't seem to mean that grass was growing. Is this a slang term?
What does it mean? I couldn't find it in any of my dictionaries.
Well, literal (笑) someday changed into 'w' especially in 2ch and such, and some people don't like ones who uses too many of them, like, ちょっwwwwwwwwwww, (this must be like "hey, wait a minulollollollollol") and they started saying 草生えすぎ, or using the AA you put above, frowned （・ω・） mowing the lawn.
So now they also use 草生えた just instead of saying "it's funny."
Thanks to @Chocolate, I was able to learn what this word means, which is roughly that something was funny. Here are a couple sources:
Why does it mean something was funny? Well, as discussed in this question, strings of