In high school chem lab, I instigated an event to hook the oxygen bottle to the gas line and blow oxygen back into the line until it got to the inevitable lit bunsen burner in one of the other labs.
Unfortunately, we had just begun the blow-back when my lookout warned us of the impending return of the instructor.
Unfortunately, we had just begun the blow-back when my lookout warned us of the impending return of the instructor.