Does anyone know the meaning of the idiom "throwing down the goblet"?

You mean gauntlet. The phrase won't seem as mysterious when you use the right word. Throwing down the goblet means you are done with the wine and upgrading to hard liquor. I've thrown down the goblet a time or two in my life. Hard liquor always rules the day over the wine.

It is correctly "Throwing down the gauntlet" which was the glove so to speak of the suit of armor, it is meant to challenge your rival to a duel, a joust, etc.

THROW DOWN THE GAUNTLET - "The English language contains two wholly different words spelled and pronounced gauntlet. The gauntlet in this expression means glove derives from the medieval French gauntlet, 'a little glove.' Knights of the age of chivalry, though not as noble as they seem in romances, did play by certain rules. When one knight wanted to cross swords with another, he issued a challenge by throwing down his mailed glove, or gauntlet, and his challenge was accepted if the other knight picked up the metal-plated leather glove. This custom gave us the expression 'to throw down the gauntlet,' 'to make a serious challenge." The other meaning of "gauntlet," as in "run the gauntlet," is derived from "the Swedish word gattloppe, from 'gat,' 'a narrow path,' and 'loppe, 'run'." "Encyclopedia of Word and Phrase Origins" by Robert Hendrickson (Facts on File, New York, 1997)

http://www.phrases.org.uk/bulletin_board/6/messages/267.html

Etymology:
From the practice of a medieval knight throwing down his metal glove as a challenge to combat.

(idiomatic) To issue a challenge.
"The competing firm threw down the gauntlet by offering a faster product at a lower price."

Related terms - take up the gauntlet

http://en.wiktionary.org/wiki/throw_down_the_gauntlet

to challenge; to defy.
Also, throw down the glove.

http://dictionary.reference.com/search?q=throw+down+the+gauntlet&r=66

Declare or issue a challenge, as in The senator threw down the gauntlet on the abortion issue. This expression alludes to the medieval practice of a knight throwing down his gauntlet, or metal glove, as a challenge to combat. Its figurative use dates from the second half of the 1700s, as does the less frequently heard take up the gauntlet, for accepting a challenge.

http://www.answers.com/THROW%20DOWN%20THE%20GAUNTLET

• throw down the gauntlet v.expr. To offer or send a challenge.

• throw down the glove v.expr. To challenge to combat.

• throw in the sponge v.expr. To give up a contest; to acknowledge defeat.

• throw off the trail v.expr. To mislead; to elude one who is in pursuit.

• throw overboard v.expr. To throw off the deck of a ship; to throw into the sea.

http://ultralingua.com/onlinedictionary/index.html?service=ee&text=throw+down+the+gauntlet

I think you mean Gauntlet.

It was meant as a challenge to a duel. The other person had to pick up the gauntlet later a glove to accept the challenge and then they had the choice of weapons

I think it means you just found out that you are drinking cheap wine:)...actually it is throwing down the gauntlet...Anubis87 is correct.