Bucky is a favourite drink of public order offenders across the Northern Celtic nations. Brewed by monks in England it's particularly popular in Scotland and Ireland. in real life it's about 14 percent alcohol and has as much caffeine as eight cans of coke.

This is a bottle of Buckwein, a traditional drink of Forsworn headcases imported from High Rock, that bears a striking similarity.

On wikipedia; https://en.wikipedia.org/wiki/Buckfast_Tonic_Wine