To masturbate the male penis. A reference to the similarity of an erect penis to the shape of a classic Bishop chess piece.
Bash the Bishop: "I caught my little brother bashing his Bishop for the first time yesterday"
di snakehands 02 luglio 2010
when you go to have a wank
as in, hes goin to aash his bishop
di bobby bobler 16 ottobre 2003