In addition, it's always bad form to call your opponent's law firm and threaten to kill one of their lawyers.
Did something like this really happen? Some Texas lawyers and law-firm staff are saying it did. You can read about it here (pdf).
While I will refrain from editorializing, I would like to add that I read through the deposition I just linked to, and it appears the trouble began when the targeted lawyer began laughing at the muy-macho lawyer's deposition questions. That threw the muy-macho lawyer off track and led to the later threats of violence.
As a public service, I offer a post from my other weblog that addresses this very problem: "Ignore Your Opponent in a Deposition."