Sam has no idea what a Borrower is, other than, apparently, a name for a tiny person, but Aglet looks self-conscious and crestfallen at having mentioned it at all. Ok, Sam can run with that.

'That's ok,' he assures Aglet. 'I know a lot of stuff I'm not supposed to know, anyway. I've never heard of Borrowers before; what are they? Or, you, whatever.'