All pop stars try to expand their audience these days with collaborations, but few this side of rapper Kendrick Lamar have opened their tents as widely as white-hatted country star Brad Paisley, who plays Nassau Coliseum on Thursday night. The singer-guitarist has had hit duets (with Carrie Underwood on "Remind Me"), goofy duets (with the great Little Jimmy Dickens several times) and poignant duets (with Charlie Daniels on last year's underrated domestic-violence rant "Karate").