If you Barge In on something, you intrude or abruptly interrupt a situation. Flat-bottomed barges have been used on the British waterways since the 17th century. Due to the cumbersome nature of these vessels, collisions were quite common and so, by the late 1800s, schoolboys used the term for bumping into somebody. By the turn of the last century the phrase had entered the language more widely, to mean to interrupt without invitation, sometimes with physical force.