To use a slang expression, they could say, "You look really cool! ""

要使用俚语他们可能会说，“你看起来真酷！”

youdao

In other words, this expression has been around a long time. It's not one of those slang expressions that come and go quickly with some passing fad.

换句话说，这种表达方式由来已久，并不是什么昙花一现的流行俗语。

youdao

Do not use obscenities slang or too many idiomatic expression when using an interpreter.

在使用翻译的时候，不要使用不雅的词语、俚语，或使用太多的俗语。

youdao

At Kennesaw State University in Georgia, the Intensive English Program doesn't teach a slang expression until it is in use for more than one generation, says David Johnson, a professor of English and director of the program.

WSJ: Mastering the Finer Points of American Slang