A person who wears a bullfeather is a person whose wife or
girlfriend has cheated on him. The term comes from the "horns" on a cuckold -- the horn being the closest thing a bull has to a feather.
Just about any joke involving horns was considered
hilariously funny through the 19th century, because everyone knew it meant the guy was a fool who was being cheated on --
the worst social disgrace for a man of that era.
John's wife is having an affair with Peter Quincy -- can't you see the
bullfeathers on his headRichard's girl sleeps with every guy
in town. What a bullfeather he is!