Christina Aguilera may not be coaching on this season of The Voice, but that hasn't stopped her from doling out advice to her former co-stars on the show.
As the show's March 25 premiere gets closer, the pop star, 32, implored mentors Adam Levine and Blake Shelton to be on their best behavior for new judge Shakira.
"[I] know how you boys can get," Aguilera tweeted March 18, "so...