Kim Kardashian’s 2012 Halloween Mermaid Costume. Kim K has done it again, and this year’s costume was fun, alluring, sexy and glamorous. She showed up at the 2012 Midori Halloween party, dressed with blonde hair, shell-like bustier, and a green sequin mermaid style skirt. I adore how creative her Halloween costumes are. She finished the look with pearl jewelry, and soft beachy makeup. Her boyfriend Kayne even got in on the action dressing up like a sailor by her side. Look below to see Kim’s full mermaid costume look.