Origin: Chinese Internet
This is a pretty funny story! The true meaning of this word is “grass mud horse”, one of the most cute and funny animal in the world (see the pic below). But “The true colors” of this word are hidden behind Cinese web censorship, as matter of fact it was used since 2009, by an article, to substitute 肏你妈 (càonǐmā) which literally means “Fuck your mother! Again Chinese internet users found a way to escape censorship.
P.S.: Be careful! Use it ONLY when you’re furious! （· ｪ ·）（· Y ·）（·´ｪ`·）
Need to know: The Ministry of Education declared this word to be vulgar internet language, in 2015 (16th October).
In Use: “草泥马！” ( Fuck your mother!)
Interesting things: After it changed the meaning, the animal became really popular and videos, merchandise, cartoons and more appeared in China.