Further to oz4m2's message: do not be mislead by this type of advertising. Over here it's known as Irish Blarney.
Guiness is a corrosive black liquid only distinguishable from Hydrochloric Acid by its black colour rather than a clear liquid that fumes. It has a simliar capacity to corrode. In younger days, when less wise, I found that if you drank more than 2 pints (some 1.1 litres for the uninitiated) it would stain your pillow as you slept or, more accuarately, passed from delirium into coma. This is because regurgitated stomach contents, when supine, lyses through your tympanic membrane and leaks onto your pillow. My mother thought I'd been polishing my brogues. So, don't be fooled join the English Temperance Movement or stick to Whisky which causes indigestion rather than encephalitis. Better still, drink 5% Spitfire bitter ale in the Castle Hotel, Trecastell, in the Brecon Beacons, along with the SAS and you can depart holding your head between your knees.
As they say in Cardiff: "Skip a day with Brain's SA" (local brewery £2.25 per pint, Angel Hotel, Westgate Street) or a sign on the back of a Cardiff taxi I saw "Make love not war; apply to driver for details".
David