butt in
butt in {v.}, {slang}
To join in with what other people are doing without asking or being asked; interfere in other people's business; meddle.
Mary was explaining to Jane how to knit a sweater when Barbara butted in.
Often used with "on".
John butted in on Bill and Tom's fight, and got hurt.
Compare: HORN IN.
Categories:
Source: A Dictionary of American Idioms
