What it means
やばい is a flexible reaction and intensifier. Depending on context, it can mean something is excellent, shocking, dangerous, stressful, or simply extreme; it is not positive by default.
How to use it
Use it in casual conversation with friends. Listen to the surrounding words and tone: やばい、おいしい often praises food, while やばい、遅刻する means there is a problem. It is too vague and informal for careful workplace or customer communication.
Examples in conversation
Where it comes from
やばい was originally used with a negative sense such as dangerous or troublesome. Its range broadened in casual speech: it can now praise something as excellent as well as intensify a bad or surprising situation. The positive sense is established, so this is not a newly emerging term.
Related slang
Further reading
We use references to check meaning and background. Examples on this page are original.