From wiki:
John Adams (born 1951) works on computer systems for AT&T, but is better known as a dedicated fan of the Cleveland Indians. He plays a bass drum during Indians games at Progressive Field.
Adams originally started to drum at Cleveland Stadium on August 24, 1973, when the Indians played the Texas Rangers. Cleveland won, 11-5. Ever since, Adams has sat in the highest bleacher seat in left center field with his bass drum, and has only missed 34 games in subsequent years.
He is the only fan for whom the team has dedicated a bobble head day.
Adams originally paid for his tickets (one for himself, and one for his drum), but recently the Indians have paid for his seats in honor of the contributions he has made to the ballpark atmosphere.
The man known by many baseball fans simply as 'The Drummer' was featured in an interview segment in a 1997 episode of This Week In Baseball.
LINK:
http://en.wikipedia.org/wiki/John_Adams_(drummer)