A Snowball is a mixture of Advocaat and lemonade in approximately equal parts. It may have other ingredients, to taste.[1]
If one does not have Advocaat, then it may be substituted by making your own Advocaat, which typically consists of 1 egg, 30 ml of simple syrup, and 60 ml of brandy. [2]
In the United Kingdom, it often comes served both in pubs and supermarkets during the winter in small bottles of approximately 180 millilitres (6.3 imp fl oz; 6.1 US fl oz) (known in the pub trade as "splits") and is usually drunk as a "winter warmer". [3]