2NE1 are a four member Korean girl group.

Above is a little Photoshop image (click to embigify, as it were) I made up of all five nails, since I can never get a decent one of the thumb. I tried to include screenshots but failed miserably, so can only link the video here and briefly explain what was inspired by what.
 The index finger was inspired by the tattoos that CL (blonde hair in the video) and Minzy (short black hair in the video) had painted on their arms. Same goes for the little finger.
Middle finger was inspired by the camoflague junglesque patterns that served as the backdrop for their video.
The ring finger was quite random. Their fanclub is called "Blackjacks". I have no idea what significance that has to them but whatever. Anyway, I guessed it was a type of card so drew one of the card symbols on it? *shrugs innocently*
The thumb is only pictured above, and that was inspired by Dara's (long brown hair, absolutely gorgeous woman) bright red lips in the video. She's my favourite out of the four and her lips were so eyecatching, I had to put them on my nails :P I used Nails Inc "Milan" from the Diet Coke colours for that design, but against the white it stamped closer to fuschia/hot pink than red. Whatever.
She's like 25 as well? Again (if you remember my Brown Eyed Girls manicure) that's quite old for an idol. I seem to like all the older women in Kpop. O_o