Meaning of だまって置いてきちゃお


I'm reading a Shin Chan strip and he and his friends are discussing who is
going to take care of the stray dog they found. One by one he asks his
friends, and they all say they can't. Then, he says (without looking at his
last friend)

> そうだ！！マサオ _んち_ だまって置{お}いてきちゃお。

Then, his friend, who is next to him, says:

> ボクいるんだけど・・・

So, in the first sentences, I don't get the **だまって** (no idea what it is) or
the **置いてきちゃお**. I know 置く as an auxiliary verb to say you're doing something
in preparation for something else, but I don't understand it in that context,
with きちゃお after it's て form.

Would be very thankful if somebody could explain to me the use of each of
those expressions in the sentence.

Here's a pic of the panel itself:

[![Panel](https://i.stack.imgur.com/D5EUR.jpg)](https://i.stack.imgur.com/D5EUR.jpg)




You sure you're quoting their lines correctly? I haven't read the strip or
seen the TV episode but found a similar dialog, in which Masao happened to be
that last friend Shin-chan didn't ask:

同じまさおくんネタなんですが  
初めてシロが登場したシーンで  
捨て犬だったシロをどうするか４人で考えてる時

しん ｢そうだ! 黙ってまさおくんちに置いて来ちゃおうか｣  
まさ ｢僕いるんだけど…」  
が最高に笑えました!

<http://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q1240826137>

Shin: "Oh, I know. How about leaving it at Masao's house without telling him?"  
Masa: "Um... I'm here."

・（X に）黙って: without telling (X) / 黙る: to hush up, shut one's mouth  
・まさおくんち = まさおくん+の+うち （cf. 先生んち、俺んとこ、あんたんとこ, etc.)  
・置く in 置いてきちゃおうか here is NOT an auxiliary verb but part of the verbal
combination 置いてくる "go and leave" (lit. "leave and come back").  
・きちゃおうか = きてしまおうか The use of 完了形 てしまう conveys not so much the sense of
completion as the daring aspect of his mischievous act (given moral
objections, risks, etc.).

