Butt in
Meaning: to interrupt or join in a conversation or activity when the other people do not want you to
Example: The interviewer kept butting in and wouldn't let me answer the question. Pardon me for butting in on your conversation, but this is important. John butted in on Tom and Jane to tell them that the mail had come.
Example: The interviewer kept butting in and wouldn't let me answer the question. Pardon me for butting in on your conversation, but this is important. John butted in on Tom and Jane to tell them that the mail had come.