whim       
noun [ C ] uk/wɪm/ us/wɪm/
C2 突然的念头,冲动
a sudden wish or idea, especially one that cannot be reasonably explained
  We booked the trip on a whim. 我们一冲动就预订了假日游。 
 You can add what you want to this mixture - brandy, whisky, or nothing at all - as the whim takes you. 你可以在这种混合饮料里加入任何你喜欢的东西——白兰地、威士忌或什么也不加——全看你自己。 
 Oh for a husband who would indulge my every whim! 啊,我多么想有一个对我百依百顺的丈夫呀! 
 Synonym: caprice