New Slang/ Idioms used among young ones in America

How long do you believe it would take for an English expression (especially idiomatic expressions) to be outdated? It seems that we are facing newly coined phrases and nouns every couple of years or faster than that here in America. This week, I would like to share some interesting expressions that are going viral today among young ones in the States. (*source from https://www.refinery29.com/2016/05/107772/cool-words-slang-dictionary-popular-sayings ) 1. lit : (adjective) cool, turned up, fun, or popping 2. to keep it 100 : (phrase) to keep yourself real and true, to be honest and stick to the way you are, no matter what any one else thinks 3. trill : (adjective): true + real/ 100% honest 4. Gucci : (adjective) Not referring to the Italian brand name here. It means ‘good, fine, or ok’ . This is a slang term mostly used by people living in ghetto or slum. e.g., What’s Gucci? =...