Unseen Academicals - Terry Pratchett
When he turned around, Madame, in a nightshirt that could have accomodated a platoon, at least if they were very friendly, was bearing down on him with a glass in one hand and the champagne bottle in the other.
"This stuff's gone horribly flat," she said.
Moral: If the clacks are so engrossing you are whizzing in cups, don't use the same style cup for your Mountain Dew.
On the bright side, you'll know if you're diabetic...
The great truths are only sold in halves, as no one will swallow them whole.