What is 'terd?
Slang for buttered; a means of serving cafenated beverages with a buttered glass. This quaint method of drink decanting originates from the outlying areas of Northern Ireland, where it remains popular to this day. The glass is lightly coated with a thin layer of butter before the beverage is added, this gives the drink a fuller flavour and a slightly oily film on the surface of the liquid.
Barkeep, a coke 'terd my good man.