Blake Shelton (left) and Adam Levine
Mario Anzuoni/Rueters/Landov
What the #$!% will Adam Levine do to clean up his language on The Voice?Start paying up.
"I have a dirty mouth," Levine, 33, one of the hit NBC show's four coaches, tells PEOPLE. "I curse a lot and I want to try to contain that a little bit."
So when the live shows start airing next month, he might institute a new policy: "I'll have a little curse jar next to me. Every time we say a bad word, $100 goes to charity. It will help us, it really will. Because we'll end up giving a lot!"
His close friend and fellow coach Blake Shelton – who appears with Levine on this week's cover of PEOPLE – is already on board.
"I like that. I'm agreeing to it," says Shelton, 35, who will also co-host the Academy of Country Music Awards on April 1. "I will sign up!"
For more on Shelton and Levine's friendship – including their clashes with Christina Aguilera and their double-date adventures with significant others Miranda Lambert and model Anne V – pick up this week's issue of PEOPLE, on newsstands now