The account at 2 Samuel 6:14 is a great example of why we trust the Greek Septuagint manuscripts over the Hebrew Masoretic text.
In the Septuagint, King David is described as wearing a fine robe (στολην εξαλλον) while he danced in the parade leading God’s Sacred Chest into JeruSalem for the first time. On the other hand, the Hebrew Masoretic text says that he was wearing just a linen ephod (vest).
So when his wife Michal accused him of exposing himself while he danced, the conclusion that the Hebrew text implies is that he celebrated bringing Jehovah’s Chest to JeruSalem by dancing naked from the waist down! This certainly doesn’t sound appropriate or likely.
However, the Greek Septuagint shows that he was fully covered in fine clothes, so Michal’s accusation could just be the exaggeration of a disgusted wife who didn’t approve of David’s dancing. Perhaps she thought that her husband was not behaving in the dignified matter that her father Saul would have done.
Therefore, did David actually expose his genitals?
Well, apparently, ancient IsraElites didn’t wear underpants beneath their robes, so lively dancing may have caused David to accidentally expose himself. But the rest of Michal’s and David’s words may just mean that she disapproved of his exuberant dancing and used exaggeration to make her point.