Well, one of your classmates may have beat you to the punch - seldom do we receive nearly identical questions from the same state on the same day. We took your questions to the experts at the National Pork Board and received the following answer:
"In pre-revolutionary New England and into the Revolutionary War, some pork cuts (not those highly valued, or "high on the hog," like loin and ham) were packed into casks or barrels (also known as "butts") for storage and shipment. The way the hog shoulder was cut in the Boston area became known in other regions as "Boston Butt." This name stuck and today, Boston butt is called that almost everywhere in the US,… except in Boston.
"Picnic ham" is a little challenging, even for the pork board folks. Generally, the shoulder is smoked, they say, which gives it a very ham-like flavor. Since picnic shoulder/ham is an inexpensive substitute for real ham (which only comes from the hind legs), they speculate that it would have been considered a good cut for casual dining - such as a picnic - rather than for use at a formal family dinner, such as Easter or Thanksgiving.