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.)
Casey Stengel suggested the term might have been derived from managers getting tired of their relief pitchers shooting the bull in the dugout and were therefore sent elsewhere, where they wouldn't be a bother to the rest of the team -- the bullpen. How serious he was when he made this claim is not clear.