Drinking was an important part of the 12th night festivities. Robert Herrick (died 1674) wrote a poem about Twelfth Night, and it included details of the popular drink ‘lambswool’. Obviously, they had different terminology than we have nowadays:

Next crown a bowl full
With gentle lamb
s wool:
Add sugar, nutmeg, and ginger,
With store of ale too;
And thus ye must do
To make the wassail a swinger.

If you would like to become a wassail swinger(!), click here for a lambswool recipe.