Why does the `请` take two duplicate words on its verb occasionally (e.g. `请洗洗你的袜子`)
quotation from 外国人实用汉语语法：
(1) the reduplication of a verb implies a short and quick 
action 

(2) expresses an attempt or trial

(3)expresses a sense of being light and relaxed

and the same goes for  [verb] +一下 

请洗你的袜子 seems to make sense in Mandarin