1. A manufacturer of chocolates. Their famous slogan is that each of their blocks of chocolate contains 'a glass and a half of millk.'
2. A person who is easily affected by alcohol. This is based on the Cadbury 'glass and a half' slogan (ie: it only takes this person a glass and a half to get drunk!)

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Any individual who cannot hold their liquor; i.e. gets drunk on a glass and a half.

Someone who gets drunk off a small amount of alcohol. Comes from Cadbury chocolate which is famous for having a glass and a half of milk in it. 'Cadbury's' only need a glass and a half (or similarly small quantity) to get drunk.

Cadbury - Someone who succumbs easily to the efects of alchohol.

A candy company that makes superior-quality sweets and chocolates.

British chocolate. Made by a company that's been around for 300 years.