Blake Shelton's last season on, and you know his old frenemy, Adam Levine, couldn't let him go without saying goodbye!Levine and Maroon 5 returned to the stage to perform their new single, «Middle Ground,» but of course, the frontman couldn't help but get a dig in when he spoke with host Carson Daly ahead of the big show.Asked if he had any advice for Blake as he departed the show, Levine quipped, «I don’t think he needs my advice.»«He's retiring, he's being put out to pasture,» Levine laughed. He’s gonna go knit sweaters.«Levine later took the mic to welcome „my dumbest friend“ to the stage celebrating his last show, „Thank god!“»Don't screw it up, you idiot!" he continued.