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.