For those who haven't read Klingon for the Galactic Traveler, bIQ ngaS HIvje' is also an idiomatic expression meaning be quite mistaken, be totally wrong.*
For instance, if you want to tell someone they're totally wrong, instead of saying bIQaghchu' You are completely in error, you could say bIQ ngaS HIvje'lIj Your cup contains water.* Using the idiom is stronger than using the straightforward way of saying it, so be careful when saying it to any Klingons.
The background of this idiom is that Klingons dislike water as a beverage; they associate water with weakness.