Definition from Wiktionary, the free dictionary
See also: buttin'
- (idiomatic) To join a conversation or situation in which one is not welcome or invited; to interject (connotes a rude or discourteous interruption).
- Hey, this is none of your business, don’t butt in!
- Forgive me for butting in.
- (transitive) to join a queue not at the end, but in the middle
join conversation when not welcome