When you hear someone talking something that is completely nonsense, it is time to use "Gǒupìbùtōng". "Gǒupìbùtōng" means "dog fart" in Chinese. When you hear someone lying to you, you can also use "Gǒupìbùtōng".
Example:
A: I lost my phone last night and... I...uh... went out to look for it...uh... the whole night!
B: That is just "Gǒupìbùtōng"!
