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: hurt {slang} {v.}