The sound a japanese cat makes. Much like the American 'meow'.

It's the sound of boredom. It plays when boredom is lurking.

An interjection often used by fangirls or chibi like art to express satisfaction, joy or any gentle happiness.

The most kawaii word from 2010 from a self demotivational and excruciatingly stressing video on youtube called 'Nyan Cat'

A very handsome boy. Who most certainly has a very cute girlfriend. A loyal boy who has never cheated on a girl.
If anyone chats crap about his girl he wont mind as he knows they are jealous of him for having a cute girl.
He is a splitting image of perfect and fit. He is adored by many but will always stay loyal.
He is the kind of guy every girl needs in their life as he cares and adores them and knows how to make them feel special.

From the popular video "Nyan Cat".

Usually used numerous times in comments on YouTube videos, especially on the "Nyan Cat" video.

After the character from K-ON! Azusa Nakano won the saimoe
2010.The campaign made a poster titled "YES WE NYAN" instead of "YES WE CAN"
The word "Can" is replaced by "Nyan"
While "Cant" is turned into "Nyan't"