I don't know what to say - You say this when someone says something so crazy it makes y

You say this when someone says something so crazy it makes your brain explode, and you're just too busy picking up the pieces to say anything.

'He said he can swim in lava. I don’t know what to say.'

'She told me she can fight a dragon. I don’t know what to say.'

'He claimed he can talk to aliens. I don’t know what to say.'