Everybody's always drinking prodigious amounts of it. They love that stuff. Falstaff lives on it.
"A good sherris sack hath a two-fold
operation in it. It ascends me into the brain;
dries me there all the foolish and dull and curdy
vapours which environ it; makes it apprehensive,
quick, forgetive, full of nimble fiery and
delectable shapes, which, delivered o'er to the
voice, the tongue, which is the birth, becomes
excellent wit. The second property of your
excellent sherris is, the warming of the blood;
which, before cold and settled, left the liver
white and pale, which is the badge of pusillanimity
and cowardice; but the sherris warms it and makes
it course from the inwards to the parts extreme:
it illumineth the face, which as a beacon gives
warning to all the rest of this little kingdom,
man, to arm; and then the vital commoners and
inland petty spirits muster me all to their captain,
the heart, who, great and puffed up with this
retinue, doth any deed of courage; and this valour
comes of sherris. So that skill in the weapon is
nothing without sack, for that sets it a-work; and
learning a mere hoard of gold kept by a devil, till
sack commences it and sets it in act and use.
Hereof comes it that Prince Harry is valiant; for
the cold blood he did naturally inherit of his
father, he hath, like lean, sterile and bare land,
manured, husbanded and tilled with excellent
endeavour of drinking good and good store of fertile
sherris, that he is become very hot and valiant. If
I had a thousand sons, the first humane principle I
would teach them should be, to forswear thin
potations and to addict themselves to sack."
It's a white fortified wine from Spain. Like sherry. Sweet, and super-powered with the addition of brandy. A cloying, super-alcoholic beverage.
And by the way. Second-rate sack was referred to as "bastard," as in, "Pour me a tankard of that bastard, mine goodly host." So, it could have been worse. Well, now you know.