San Antonio's leading Spanish-language radio station could be forced off the air or face fines over a quirky controversy juxtaposing immigrants and green limes. A recurring segment started five years ago by KROM-Radio "Estéreo Latino" involves people calling in to report sightings of immigration agents in the city. The station's disc jockeys then alert listeners, particularly undocumented immigrants, to steer clear of the named locations. No actual mention of federal agents is made — DJs speak of limones verdes, or "green limes," a euphemistic reference to Border Patrol agents, who traditionally don olive-green uniforms and drive green-lined SUVs. Curiously enough,...