Weak, strong or Navy?
In Peter's Room, when Rowan and Nick are having heir midnight bonding session over cocoa and an abandoned lamb, Rowan asks Nick* whether she wants hers "weak, strong or Navy." I've never heard the expression otherwise, and can't make up my mind whether Navy implies "extra strong" or "medium." Does anyone know for sure?
*or possibly the other way round - no book to hand.
*or possibly the other way round - no book to hand.