talk through one's hat

Etymology
Attested from the late 19th century in the in the sense of “bluff”; the sense “speak without authority or knowledge” developed later. Although some people speculate a connection to a former requirement that British Members of Parliament wear hats, the connection is implausible.

Verb

 * 1)  To speak lacking expertise, authority, or knowledge; to invent or fabricate facts.
 * 2)  To assert something as true or valid; to bluff.
 * 1)  To assert something as true or valid; to bluff.
 * 1)  To assert something as true or valid; to bluff.

Translations

 * Dutch:
 * Finnish: puhua läpiä päähänsä
 * French: ,
 * German:, wie der Blinde von der Farbe reden
 * Polish:
 * Spanish: hablar por boca de ganso
 * Swedish:


 * Finnish: puhua vastoin parempaa tietoaan
 * German:, , zum Narren halten


 * Swedish: