小时候披着床单扮公主
[xiăo shí hòu pī zhe chuáng dān bàn gōng zhŭ]
It recalls fond childhood memories: 'As a Kid, I Used To Dress Up As A Princess With A Sheet'. Many children love to dress up as royalty, often using items they find around the house for costumes, so this username captures an amusingly nostalgic moment in time.