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)