A perlocutionary act is a speech act that produces an effect, intended or not, achieved in an addressee by a speaker’s utterance.
Here are some examples of perlocutionary acts:
Searle, John. 1969.Speech acts: An essay in the philosophy of language. Cambridge, England: Cambridge University.
Crystal, David. 1985.A dictionary of linguistics and phonetics. 2nd edition. New York: Basil Blackwell.