From Longman Dictionary of Contemporary Englishbutt in phrasal verb1 INTERRUPTto interrupt a conversation rudely Stop butting in!2 INTERFEREto become involved in a private situation that does not concern you on They don’t want outsiders butting in on their decision-making. → butt→ See Verb table
Examples from the Corpus
butt in• Will you please stop butting in!• Mom, Joe keeps butting in and he won't let me finish my story. 