Basket case
Even the John Hughes classic The Breakfast Club uses the phrase “basket case” to describe Ally Sheedy’s social outcast character. The term actually comes from WWI slang, and refers to soldiers who were so seriously injured you could fit them in a basket.
Long time, no see
You might think this is a cute thing to say to someone you haven’t seen for a while. It actually derives from the greeting of a Native American man talking to early settlers. Non-native English speakers, or anyone new to a language, will make these kinds of errors in syntax. “No can do” is a similar phrase that’s said to derive from Chinese “broken” English. Both are unkind phrases to use.
On the other hand, these slang words from 2019 are worth knowing!
Gyp
You might say you got “gypped” if you get ripped off, but the term is said to refer to Gypsies. In that sense, the term derives from stereotyping this ethnic group as thieves and swindlers. Don’t use it.