I've never heard of Burgerbrau

This is the Czech beer they had on tap at the New Prague, MN 'Dozinky' days. I can't say I've ever heard of it, and I've lived in the Czech Republic for more than 10 years.

Seems that the B.B. stands for Budweiser Bier, and the brewery in Ceske Budejovice that makes it claims that it's the oldest beer with the name "Budweiser".