Salon.com
The Butte Copper Kings of the Pioneer League offered free admission to anyone belonging to a group insulted by Atlanta Braves reliever John Rocker in a December, 1999 Sports Illustrated interview.
That night they had their best attendance of the season as 676 fans (presumably some not mentioned by Rocker in the interview, and thus having to pay in order to see the ballgame) watched the Copper Kings get slaughtered by the Idaho Falls Padres, 18-6.
Among those eligible were
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Kids with purple hair
Queers with AIDS
Dudes who just got out of jail for the fourth time
20-year-old moms with four kids.
http://sportsillustrated.cnn.com/features/cover/news/1999/12/22/rocker/