He talks through his hat
چرت و پرت میگه.
Talk through one’s hat
Talk nonsense; make exaggerated or inaccurate statements
e.g.
He always talks through his hat and you never know if you can believe him or not.
او همیشه چرت و پرت میگه، و نمیدونی حرفاشو باور کنی یا نه.