Those dumbasses went swimming at the beach during the storm.

dumbasses 是由 dumb（愚蠢的）和 ass（驴子，俚语中常指"蠢人"）组成的复合词，加上复数后缀 -es。dumbass 是粗俗俚语，指"非常愚蠢的人"，语气比单纯说 dumb 或 stupid 更强烈，带有轻蔑色彩。