Je ne sais quoi – “I know not what.”

Until today, I never know the literal translation of Je ne sai quoi.

Jesus. How many other phrases do I know when to use despite not knowing what they mean? And how many phrases am I using wrong but nobody’s told me yet?

It’s like in Anchorman when Ron Burgundy kept trying to work out the proper context to use the phrase “Oh well, when in Rome.”