The B stands for Barney, as the German name of the fictional The Flintstones character Barney Rubble is "Barney Geröllheimer" and he was nicknamed after him because of the similarity to "Felsenheimer".
"B"-ul vine de la Barney, din moment ce numele german a personajului Barney Rubble este Barney Geröllheimer, iar el a fost poreclit așa datorită similarității cu Felsenheimer.