Leprosy?

I heard the strangest expression this weekend. I thought the speaker was just mixing Southernisms, but apparently, it's a legitimate turn of phrase.

talk someone's arm off
idiom
Talk so much as to exhaust the listener. The expression implies that one is so bored by a person's loquacity that one's arm falls off; it dates from the first half of the 1900s.
"talk someone's arm off." The American Heritage® Dictionary of Idioms. Houghton Mifflin Company, 1992. Answers.com 27 Feb. 2006. http://www.answers.com/topic/talk-someone-s-arm-off