LOLcat refers to pictures of cats you find all over the Internet accompanied with funny captions¹, typically with misspellings and incorrect grammar. Its use in this way is known as "lolspeak" or "kitty pidgin". 

 

“欢乐喵星人”指，你在网上发现的那些标有搞笑文字说明的猫咪照片，文字说明中通常还掺杂着拼写和语法错误。这种故意错误被称作“欢乐文”或“喵星文”。

 

The term is a composite of "LOL," which stands for "laugh out loud," and "cat," and the adorable images the word describes are an Internet phenomenon. 

 

这个词是由LOL，即laugh out loud（大声笑），和cat两个词合成而来的。萌萌的“欢乐喵星人”图片已成为一种互联网现象。