Barcelona fans are often referred to as culés. It's supposed to refer to non-member supporters, but it's been used to describe all Barça supporters.
The top-row of Les Corts was the origin of the nickname culé, derived from the Catalan cul (English: arse), as the spectators at the first stadium, Camp de la Indústria, sat with their culs over the stand. The English author, Phil Ball, notes that "all you could see was row upon row of bums".
ETA: The sign was in English.
This post was edited on 12/16 at 3:30 pm