What's your favorite non-scriptural, non-historic Mormon myth or ridiculous promise?

Let's keep out the classicals like Cain as Bigfoot, or the missionary that obeyed not getting into the water and his companion drowned.

Mine is the promise of learning a whole new language bc of reading the whole BoM in that language. So I bought my BoMs in French, Portuguese and German. Guess what. After the deception, I thought about the books without Latin characters. What about Korean, Chinese, Japanese, Thai, Cambodian?

I learned more Portuguese in 10 days in Brazil and 3 months in Duolingo, than a whole year with the BoM.