An injunction could not stand where there was inadequate service. The Yolo County District Attorney obtained a permanent injunction by default against The Broderick Boys, a street gang, that prohibited members from associating with one another within the specified locale and imposing a curfew on them. Appellants had standing to contest the injunction because they would be sufficiently aggrieved by its terms and were not required to admit membership in the gang. The injunction could not stand as there was inadequate service. Only one gang member was served and he was of unknown standing in the gang so it could not be demonstrated that other members thereby would receive notice. Because the gang does not meet the statutory definition of an unincorporated association, i.e., the evidence does not show that it was formed for a legal purpose, service allowed for such an entity is insufficient.