Originally, the Boston Crab was called the "Back breaker".  I suspect, that some early wrestling announcer dubbed it the Boston Crab OR some wrestler from Boston, used it as his finishing hold and he started calling it the "Boston Crab" and the name just stuck.
 
Same holds true for the "Irish Whip".  But, this time it was the Irish wrestlers that somewhat patented the name.
Coincidentally, there is a huge wrestling promotion in Ireland, that goes by the name Irish Whip.