According to correspondence theory, if you say or think something that does not correspond to reality then you have said something that is false. While this is an obvious concept learned in childhood, and while is true that we say many things that are false, we seldom say that ‘something is false’ — at least in Spanish. Instead, we distinguish between different types of falsities and use the idiomatic expression most appropriate to the situation.
The sophist falsity
If somebody say things that consist about fallacious arguments, sophisms or false statements with the objective of gaining reputation or prestige we may say either that he chamuyó or verseó; or that he is a chamuyero, versero (the correspodent adjectives). The former comes from caló chamullar while the latter comes from verso (verse, because of the idea that often a verse can be sweet to the ear but with a false content).
What English idiomatic or slang words fit best for the description I gave?
Be careful because the words sometimes could be used with the meaning of seduce or charming which often have a positive connotation. I think a lot of terms which fall into this category: sweet-talker, enchanter, delighter, etc. But the most usual sense is negative.
The words could be confused with an adulation. But this one focuses on the listener, while chamuyar focuses on the speaker. The idea behind the word is not that you are ‘specifically and constantly’ interested in someone, but that you are under pressure (e.g. an exam or a presentation) and you utter a nice discourse in order to (try to) show that you know what you are asked for. I found: flattering, charm the pants off, licker. But I think these terms are synonyms of adulate.
A: —How would you explain that a diode performs poorly at higher frequencies? What happens?
B: —The diffusion capacitance predominates. [Thinking that because he used the term difussion capacitance then A will be convinced that the answer is good]
A: —That's chamuyo / verso. I'm not asking how can you model a diode, but what represents the capacitance in the model of the diode that was given in the lecture.
Maybe ‘that's bullshit’ could be used, but this word is much more aggressive.
A: —I can't believe that X got his project approved by the committee. The stats and numbers he presented are nonsense.
B: —What a chamuyero/versero he is! [said as a complain]