Phrasal verbs, also called two-word verbs, are idiomatic expressions wherein the second element of the verb (the adverb or particle) is not necessarily predictable.
Phrasal Verb:
stir something up
Meaning / Example:
1. to mix something by stirring. > Please stir the pancake batter up before you use it.
2. to cause trouble. > Why are you always trying to stir trouble up?