Believe the bluff is an idiomatic phrase that means to fall for a deceitful or false statement. There are many synonyms that can be used to express the same or similar meaning. Some of these synonyms include: swallow a lie, accept a sham, buy a fake, fall for a con, be taken in by a spoof, get fooled by a pretense, and be hoodwinked by a trick. Regardless of the specific term used, all these synonyms refer to being manipulated into believing something that is not true or real. It is important to be cautious and skeptical in order to avoid being deceived by a bluff.