Guinness myself, but only if it's pulled in Ireland and only then if it's pulled properly.
Good trick with Guinness (and maybe other stouts) when you friend has left to go to the toilet and has left his fresh pint sitting on the table. Make sure the pint has formed that skin it gets on the top surface of the head, place a beermat on top of the glass and leave it for a second or two for the head to stick to it. Pull quickly, vertically upwards to remove the head completely.