Refers to having a pointless debate with somebody utterly ignorant of the subject matter, but standing on a dogmatic position that cannot be moved with any amount of
education or logic, but who always proclaims victory.
Origin:
"Debating creationists on the topic of evolution is rather like trying to play
chess with a
pigeon; it knocks the pieces over, craps on the board, and flies back to its flock to claim victory." -- Scott D. Weitzenhoffer (From an Amazon.com book review)
Man, trying to explain to those moon landing deniers that the
Apollo program was real is like playing
pigeon chess -- all they do is knock the pieces over and crap on the board.