Aphthous stomatitis (Canker sore). shallow ulcer with a white or yellow center and red border; seen on the inner side of the lip and cheeks or on the tongue; it begins with a burning or tingling sensation and slight swelling; painful; usually lasts 7-10 days and heals without a scar. î î î.
It was all a cheap publicity stunt. One of the regulation features of early ballparks, supposedly, was a gigantic billboard advertising Bull Durham tobacco, inevitably located out in left field, near the pitchers' warm-up area. Hence the bullpen was the pen near the Bull. (Which, frankly, sounds like a lot of bull to me.)
It could have also come from the Italian word for head and boss, capo. According to the Duden, it is derived from the French word for Corporal (fr:Caporal). Pulitzer prize winning journalist Robert Dennis McFadden believes that the word Kapo is derived from the German word Lagercapo meaning camp captain.