What in the world?

In a new twist on the traditional headband, Mary-Kate Olsen arrived at a non-profit event in New York wearing a thick, velvet ring around her head.

The 21-year-old former "Full House" star turned fashion designer/Hollywood party girl wore the strange headpiece to the New Yorkers for Children's "New Year's in April: A Fools Fete" at the Mandarin Oriental hotel.

She also wore a glittery floor-length gown that was several times too big, according to photos posted on JustJared.com.

The non-profit's mission is to improve the lives of children and families by increasing the private sector's awareness of child welfare issues.

Click here to read more on this story from JustJared.com.