When people peeve about words they hate, the same kinds of words crop up repeatedly, such as business jargon, colloquialisms, and slang. Young people are often the main creators and distributors of these new words and phrases. They may use them to signal group identity, as John E. McIntyre writes, or to express themselves or indicate their mood or personality.
There’s nothing inherently bad about this. We all do the same thing for the same reasons, more or less, though in doing so we may be less inclined than young people to use novel or trendy language. Recently I saw someone on Twitter tearing into bae and fleek, saying they were ‘stupid words’ and ‘non-words’ that made their users ‘sound like idiots’. This is unfair (not to mention self-contradictory). Unless our aim is to be abusive, we can dislike words without insulting or upbraiding people. We can simply avoid using the words ourselves and move along.
Whether bae and fleek become a stable part of the common vocabulary, or instead fade from popular use to become old hat, is something we don’t yet know for certain. So it makes sense to reserve judgement about usages like this – not to condemn them before they’ve had a chance to either disappear or prove useful additions to the language over a longer time period.
I haven’t added bae or fleek to my active vocabulary, and have no immediate plans to, but I have added other new usages. I find hangry (and the related noun hanger) a handy jocular word to describe the feeling of irritation due to hunger. Other relatively new additions to my idiolect include because X and throw shade – though on the occasions I use these I do so chiefly online, where they’re more familiar to people.
Curious about what new usages other people have adopted, especially in speech, I asked on Twitter and got lots of interesting replies: FOMO, spendy, mansplain, OMG, adulting (doing grown-up things), X is a thing (meaning X exists or is a recognised phenomenon), janky (to describe something that works but not quite to expectations), negciting (exciting but in a negative way – this one was new to me), and rando (a random person, in Ireland often called a randomer). Mansplain – and more generally the splain libfix and its other derivatives – is one I’ve found useful since drawing attention to it here three years ago.
What new slang and other expressions have you added to your vocabulary? And what terms are you eyeing up for possible adoption?

My favorite use of because NP is because language change.
I saw randos on the Internet on an ad the other day, and thought it was a typo for randoms, which has long been in use among hackers to mean ‘people I don’t know or have no particular reason to respect’. But I guess not.
John: As I understand it, rando means more or less the same thing as the random (n.) you describe. It’s often a neutral reference, but it may also connote mild disparagement or dismissal.
I saw an example of because [pronoun] yesterday: “[David] Cameron happens to be right on this one, and people writhe to disagree anyway because him.”
John: There are a couple of hundred citations for ‘rando’ in the big enTenTen corpus and of course, being often spoken and fairly recent, it will much more frequent IRL. It feels a bit more disparaging than ‘random’ to me. It’s recently been added to the Open Dictionary and will be published next week.