Full of Hot Air adjective phrase informal
Used to describe a person who talks a lot, but does not say any meaning or value
Don't believe him. He's just full of hot air.
Lisa is full of hot air. You know, she always boasts about how much money she has made.
Nonsense
This idiom first appeared in the later half of the nineteen century. It was first mentioned in Mark Twain's 1873 book Gilded Age: " The most airy shemes inflated the hot air in the Capital."