「首をひねりたくなる」はどの意味ですか。
「彼の発言には首をひねりたくなるよ。」には「首をひねりたくなる」はどの意味ですか。

Question

Answer

「疑問を感じている」ということです。由来はちょっとわかりません。

Answer

I don't get his point very much.
What he means (is saying) doesn't really make sense to me.

So it's like, people kind of understand his opinion, but not very agree with it, and think still need to consider it because he failed to convince them enough.