For in the hand of the Lord there is a cup, and the wine is red. The "cup of God's fury" is a frequent metaphor with the prophets (Isaiah 51:17, Isaiah 51:22; Jeremiah 25:15, Jeremiah 25:17, Jeremiah 25:28; Jeremiah 49:12; Lamentations 4:21; Ezekiel 23:31-33; Habakkuk 2:16, etc.
); and is commonly represented as full of wine, which his enemies have to drink. The "redness" of the wine typifies the shedding of blood. It is full of mixture. Mingled, i.e; with spices, and so made stronger and more efficacious (see Proverbs 9:2; Proverbs 23:30; So Proverbs 8:2; Isaiah 5:22).
And he poureth out of the same. God pours out the cup of his fury on all nations, or persons, whom he chooses to afflict, and they are compelled to drink of it (Jeremiah 25:15-28). But the dregs thereof, all the wicked of the earth shall wring them out, and drink them.
To drink a cup, dregs and all, is to empty it wholly, to swallow down all its contents.