"Swag" describes a person who is cool or enviable, or someone can "have swag." But it hasn't been trendy since 2012, teens say.
Source: Urban Dictionary, Business Insider survey
Now, teens are more likely to express something that's cool as "lit." It's slightly different than swag in that it's not typically used to describe a person; a situation or thing is more likely to be described as "lit."
Source: Urban Dictionary, Business Insider survey
"Bae" comes from African-American Vernacular English (AAVE) pronunciation of "babe." It used to be the ultra-popular way to refer to your significant other, but teens say it's now overused.
Source: Urban Dictionary, Business Insider survey
There isn't a trendy word to use instead of "bae," actually. But if you want to call a friend something other than their names, teens recommend "bruh."
Source: Urban Dictionary, Business Insider survey
Drake popularized "YOLO" in his 2012 song "The Motto." It means "You only live once," and became trendy as a phrase to justify seizing the day.
Source: Urban Dictionary, Business Insider survey
DJ Khalid takes the credit for 2018's rap-popularized slang: "key" or "major key." This can be used to describe anything that's essential or important.
Source: Urban Dictionary, Business Insider survey
"Rad" is yet another synonym for cool, and teens say it's totally out-of-touch. In fact, it hasn't been trendy since the 1990s.
Source: Reddit, Business Insider survey
A better way to say something is cool is "chill." A person, situation, or thing can be chill, and it doesn't necessarily mean relaxed or calm.
Source: Urban Dictionary, Business Insider survey
Teens also picked "gnarly" as a word that no one should ever use. It's another synonym of "cool" that dominated in the 70s and 80s.
Source: Reddit, Business Insider survey
"Savage" refers to someone who acts ridiculously and without restraint, but it's usually at least somewhat admiring. They often do what everyone else wants to do if they weren't scared.
Source: Urban Dictionary, Business Insider survey
But savage is out. If you want to express sympathy with a friend who is in an unfortunate situation or got hurt (perhaps by someone who is savage), teens recommend "oof."
Source: Reddit, Business Insider survey
"On fleek" describes something that's perfect. It also came from AAVE, and was popularized by a 2014 Vine video where the user brags about her "eyebrows on fleek."
Source: Merriam-Webster, Business Insider survey
A trendier word to describe something that's perfect is "GOAT." That's "greatest of all time."
Source: Bustle, Business Insider survey