Incidental: something that happens in connection with something else, but is less important 附带的次要事情
You'll need money for incidentals such as tips and taxis. 你将需要准备好付小费和乘出租车之类的杂项开销。
Buffer: a thing or person that reduces a shock or protects somebody/something against difficulties 缓冲物；起缓冲作用的人
Support from family and friends acts as a buffer against stress. 家庭和朋友的支持有助于减缓压力。
She often had to act as a buffer between father and son. 她常常不得不在父子之间扮演调解人角色。
a buffer state(= a small country between two powerful states that helps keep peace between them) 缓冲国(两敌对大国之间有助于维持和平的小国家)
a buffer zone(= an area of land between two opposing armies or countries) 缓冲区（两敌对军队或国家之间的地区）
make a killing: to make a lot of money quickly 发大财;获取暴利;财运亨通
来源:恒星英语-口语频道