Meaning of 自己被收拾得乾淨漂亮 in context and significance of passive voice I am reading a novel linked below and there is a phrase the meaning of which is not entirely clear to me. To provide a little context, the phrase refers to the 12 year old girl Xiaofu, who has just confessed she is in love with her brother and her brother has replied "me too". The phrase itself reads:


  知道那天自己被收拾得干净漂亮，便大胆地回过头来，让他看。


Does it mean she knew that she was neatly dressed that day, or does it mean that she put her love life neatly in order? I think the second can't be correct, but for the first one I also don't understand, why passive voice was used. The protagonist is 12. Surely she wasn't dressed by someone else! My best guess at a translation would be:


  knowing that she was neatly groomed that day, she turned around more emboldened for him to behold. 


For context, the rest of the passage, which I think I understand, reads:


  小芙撇了撇嘴，突然柔声说道：“炯，我很喜欢你呀！”
   炯害羞地低着头。半晌，他抬头看妹妹，点了点头，用轻微得连他自己都难以听到的声音说：“我也是。”
   小芙快乐得一下子跳了起来，沿着山坡疯跑。跑到山谷底下站住了，知道那天自己被收拾得干净漂亮，便大胆地回过头来，让他看。


If anyone wants even more context, here's a link to the relevant section of the novel, the entire work can be read there.
知道那天自己被收拾得干净漂亮


The author left out the subjects because they are very obvious.  The sentence 
will be easy to be understood if we add them back as follows.

(她)知道那天(她)自己被收拾得干净漂亮。

她 she
知道 know
那天 that day
她 she
自己 herself (not another girl)
被收拾得 be put in order
干净 clean
漂亮 beautiful

(她)(知道)(那天)(她)(自己)(被收拾得干净漂亮)
(She) (knows that) (that day) (she) (herself) (was neatened clean and beautiful)

She knows that she herself was neatened clean and beautiful that day.
She knows that she was neatened clean and beautiful that day.

收拾 means 整理 - to put things in order; to order; to tidy; to neaten.
For example, to clean the face, to comb the hair, to sort the clothes, etc.
It does not necessarily mean to apply cosmetics or to put on another more beautiful clothes.