Fire Doors.

Ada the office Tea Lady wiggles herself and her clanking trolley backwards pushing open a fire door with her Behind. A critical smoking office worker supplies a door wedge and mocks the rules about keeping the door closed at all times. Due to carelessness they stubs out a cigar before they leave the office. After the building has burned down rescued sheepish Tea Lady Ada is subsequently seen being handed a cup of tea by a sympathetic fireman.