Posted by Charles Hines on April 25, 2008 at 08:37:
"Son of a gun"
While in the Navy, I had read that this phrase was purported to have its origins from the practice of using the firepower of armed ships, i.e. cannons, guns, etc., to create an impact on the ship. This was believed to cause pregnant women who were in labor to speed up the delivery of a child. Thus, the child would get the nickname of "son of a gun". I may have read this in a phrase book called "A Hog on Ice" and even perhaps the 2nd volume of it.