Spain is bracing for a nationwide bring-a-bottle party that authorities, at least, do not view as a cause for celebration. Teenagers are preparing to gather in some 20 cities across the country this weekend for mass drinking sessions. The booze-ups are in defiance of measuresto curb what is a growing trend. The Spanish government is becoming increasingly worried about the parties, known as “botellons”Health Minister Elena Salgado says she wants young people to reflect on whether illegal drinking is the best way to entertain themselves. The botellons are popular with teenagers and students who cannot afford to buy alchohol in bars and clubs. But authorities say it is making streets and parks in some cities no-go areas for other residents.