I was walking through Sawtooth Cauldron, and got an ECHO recording with the following dialog:
Handsome Jack: So what's this Zero guy doing on Pandora in the first place?
Angel: I dunno.
Handsome Jack: Angel, you've got a brain the size of a planet. Don't give me 'I dunno.
Angel: From what footage we have of him, I can't even tell if Zero's human or not.
Handsome Jack: W-w-what do you mean, not human? Is he a robot? An alien? What?
Angel: I dunno.
(Copied from here)
I originally interpreted this as Angel's computer "brain", which could be huge for all we know.
At this point in the story though, we already know that Angel
is a siren, not an AI; and obviously Jack knew this all along.
As you can see from the image below:
Her head is clearly not the size of a planet, since this image is from when she's standing right in front of you.
What does Jack mean by this?