What is this use of てしまう in this sentence?


[![manga](https://i.stack.imgur.com/UhY2G.png)](https://i.stack.imgur.com/UhY2G.png)

So the character with blonde hair got asked by a girl in class A to ask the
guy with black hair about his type.

However the guy with black hair says he doesn't have any example to give him

好きになった人がタイプとかそういうイケメン回答しちゃうかあ

My interpretation of the text is that he suggests to give the girl an "ikeman
type" of answer such as "好きになった人がタイプ" .

However, I'm slightly confused on why he used しちゃう.




> 好きになった人がタイプとかそういうイケメン回答しちゃうかあ
>
> I might end up giving an ikemen answer like "my type is the girl I am in
> love with".

しちゃう adds some playfulness and gives the idea of a less deliberate action.
It's kind of like teasing someone. It's fairly common in this type of
situation (informal, friendly).

