In many countries, especially those formerly part of the former British empire, a brigadier is either the highest field rank or most junior general appointment, nominally commanding a brigade.
A "Beerbrigadier" is the highest rank pisshead amongst a band of alcoholics on a "pub crawl". The ruling "Beerbrigadier" of the beer brigade decides what pub is best, what beer is tastiest, and what fat slag is worth shagging.
"Look at that fellow, he just drank 11 pints of ale! He must be a beerbrigadier!"
"Onwards to the next pub! Follow the beerbrigadier!