Perhaps I'm wrong, but I've always remembered this as

    *Ugly* bags of mostly water.

Am I wrong?

And along with several other commenters here, I strongly dislike this sort of multi-direction navigation with no overall map showing what's there, where I've been, and what I haven't yet visited. Beautifully designed and presented, with no concern for the user experience.

A bit like the cars being described.

    The car is designed  | The presentation is
        perfectly.       |     designed perfectly

    Any crashes are the  | Any inability to navigate
        driver's fault.  |     is the user's fault.

EDIT: The Wikipedia page about this episode agrees with me, but other "quotation" pages have "ugly giant bags of mostly water." Does anyone have the episode to hand and the time to watch it? Am I paying too much attention to trivial details?

EDIT II: Found a script[0]: First reference is in an initial translation and is:

    Ugly... Ugly... Giants...
    Bags of Mostly Water...

Subsequently as the translator gets better it's:

    Ugly Bag of Mostly Water

So there we are.

EDIT III: Wow - downvotes! No complaint, obviously people feel either that this comment is wrong, or doesn't belong. I'd appreciate knowing why people might think that, but I guess I'll never know. Which is a shame, I'd welcome the opportunity to learn.

[0] http://www.st-minutiae.com/resources/scripts/117.txt