[xià liú]
（下游） lower reaches (of a river)
the lower reaches of the Changjiang River
长江下流
（卑鄙龌龊） low-down; mean; off colour; near the bone; obscene; dirty
base acts; low-down behaviour [tricks]
下流的勾当
scurrilous attacks; coarse invectives
下流的谩骂
dirty jests; obscene jests; coarse jokes
下流的玩笑
talk dirt
说下流话
write dirt
写下流作品
The jokes he told were quite off colour.
他说的笑话很下流。