Hook line and sinker意思

"Hook, line, and sinker" is an English idiom that means to be completely fooled or taken in by something, usually by someone's persuasive argument or story. The phrase suggests that the person has been caught by the hook (the bait), the line (the means of being drawn in), and the sinker (the weight that helps the bait sink, making it more believable), just as a fish might be caught by a fisherman's hook, line, and sinker.

For example:

"She told us the story about the haunted house, and we bought it hook, line, and sinker."

In this example, the listener(s) were completely convinced by the story, to the point of believing every detail without questioning it.