This is a truly horrible puking sort of a word.
I'm not sure why it's so nasty because milk and silk are, well, milky and silky. And the bill bit is fine, too (unless, obviously, it's a demand for payment).
Anyway, bilk. It can mean to thwart, or to refuse due payment, or to cheat.
In the card game of cribbage, it's playing a card which stops your opponent from scoring in his or her crib.
(I suppose bilking at cribbage is part of the game, but, I don't know, I think I'm too soft-hearted to take any pleasure in it even then. Perhaps it should be re-named. Plurdling, perhaps.)
Anyway, how could a bilk-free Sunday fail to make the world a happier place?*
Word Not To Use Today: bilk. This word is probably a form of the word baulk. It comes from the Old English balca, which is related to the Old Norse bálkr, partition, and the Old High German balco, which means beam.
*I'll make an exception in the case of the veteran clarinettist Acker Bilk, who, as far as I know, is perfectly harmless.