Baltimore holds an important place in plunk history. Don Baylor recorded 46 of his 267 HBPs while playing with the Orioles, and Hughie Jennings recorded 205 of his 287 plunks with the Orioles... but not the same Orioles. The current Orioles franchise began life in the American League as the Milwaukee Brewers in 1901 but grew out of that by 1902 and became the St Louis Browns. They moved to Baltimore in 1954 and took over the name Orioles which had been unused since 1900. Hughie Jenning's Orioles played in the National League from 1892-1899 and the American Association before Jenning's got there. They were reportedly an impressive and pretty funny bunch of cheaters. Maybe the problem with modern day cheating is the lack of crowd participation. In 1900 the National League contracted, dropping four teams, and Baltimore wouldn't have Orioles* for another 54 years.
*See comments for correction.