talk through the back of your head

talk through the back of (one's) head

1. To speak nonsensically or foolishly. No, we didn't see a kangaroo driving a car—he's just talking through the back of his head again.
2. To exaggerate one's achievements or knowledge of some subject; to bluff or boast. Dorothy keeps saying she can outrun anyone in our school, but she's talking through the back of her head if you ask me. It seemed like the candidate was talking through the back of his head for a while when the debate turned to the topic of tax policy and law.
See also: back, head, of, talk, through
Farlex Dictionary of Idioms.

talk through the back of your ˈhead

(informal) talk nonsense: If he says that he’s going to win the prize, he’s talking through the back of his head.
See also: back, head, of, talk, through
Farlex Partner Idioms Dictionary
See also:
  • talk through the back of (one's) head
  • talk out of the back of (one's) head
  • bump (one's) gums
  • forever
  • a fool at 40 is a fool forever
  • make a big thing (out) of (something)
  • get off it
  • Get off it!
  • come off it
  • Come off it!