"Unring the bell" is a good analogy which can save a lot of words in making the point. That phrase originated, as far as we can find, in Sandez v. United States , and was elaborated on in Dunn v. United States, which added other pertinent analogies. "After the thrust of the saber it is difficult to forget the wound," was another, and then the most colorful one of all, "If you throw a skunk into the jury box, you can't instruct the jury not to smell it." In the present case there was no skunk thrown in the jury box. As also mentioned in Dunn, "Trials are rarely, if ever, perfect, but gross imperfections should not go unnoticed." We find no gross imperfections which would overpower the district court's instruction to the jury to disregard Lowis' statement.