in one's birthday suit 不是穿着某人的生日套装

【例句】The child was in his birthday suit and ran around the yard. 【误解】这孩子穿着生日那天买的服装在院子里到处跑。 【正确】这孩子光着身子在院子里到处跑。 【说明】in one's birthday suit意思是“光着身子”、“一丝不挂”、“赤条条的”。