what are you talking about
Tom ni siquiera sabe de qué estás hablando.
Tom doesn't even know what you're talking about.
Sé exactamente de qué estás hablando.
I know exactly what you're talking about.
Tú mismo no sabes de qué estás hablando.
You don't even know what you're talking about.
No tengo idea de qué estás hablando.
I have no idea what you're talking about.