This is from one of the trial attorneys who are part of the community here - remembering the delightful lectures of Prof. Irving Younger, the foremost teacher of the skill of cross-examination, whose videotaped presentations are still being used to train new lawyers, even years after his death. One of Prof. Younger's more memorable illustrations of the line that one may not cross in questioning a witness has to do with the concept of a "good faith basis" for any question that you ask. As an example,
when you ask someone, in court, about a scandalous accusation, you must have a substantial reason for advancing the claim. Thus, in his words, before you ask "Is it not a fact that you regularly have sexual intercourse with a parrot?" you should be able to cite your proof - as the Prof. said (snarkily), when you are called upon by the Judge to justify the question, "Well, Your Honor - here's the parrot!"
Mr. Cantor initially claimed that his campaign headquarters were shot at several days ago, but there hasn't been any confirmation, by physical evidence or otherwise, that there is a word of truth in what he says. So, Mr. Cantor, Where is the Parrot?