Do you know what Eggnog is? Aside from that it's a sweet Christmassy drink, I'm not sure I did. In a recent survey Waitrose Cellar found that 96% of people don't actually know, so I don't feel too ignorant.    Essentially, eggnog is a egg based drink blended with cream, sugar, alcohol and spice and I promise it is much much nicer than it sounds. Also - it's not even American, which seems to be an overriding misconception: it originates from East Anglia. Who knew?   Anyway, Waitrose Cellar are