Once, the man sitting next to me on an RJ was football player sized. His chest encroached on my seat. I quietly went to the galley, where the FA agreed it wasn't right. She called for the GA to escort the man off the plane. While we were waiting, the pilot asked why I was there, the FA told him and he agreed I couldn't sit there and the man would have to be removed. It was a full flight with one broken seat. A maintenance guy walked up to the door and asked why the door hadn't yet closed. The pilot explained. The maintenance guy asked why the large man wasn't moved next to the broken seat, which would solve everything. The FA quickly spoke to him, he gladly moved and we were off an in the air in no time. Not only was it solved in a non-confrontational manner, and, at not time was I going to be the one tossed off the plane, but it made me think the right person was doing the plane maintenance, as he was the only one who understood how the pieces should fit together!