The pair are judges on the hit NBC competition series, alongside John Legend and Blake's girlfriend and the band's singer Gwen Stefani - whose track kept mysteriously playing throughout Monday's (September 30) episode, interrupting the "Since U Been Gone" star.
While the coaches were in the dark about where the music was coming from, Blake revealed in a confessional clip he was behind the trolling, after Kelly blocked him from securing an act he wanted on his team.
"The 'Don't Speak' music – it was me," he laughed. "I can't wait to do it again because Kelly blocked me. She can kiss my butt."
However, the country crooner was caught red-handed when he accidentally hit his button and set off the anthem, as he sighed: "Dang... I derailed everything!"
"You're a liar and a cheater. I can't believe it's you," Stefani said of the stunt, while "All of Me" hitmaker John added: "I don't know how Gwen can be in a relationship with someone who has this hard of a time telling the truth."
"I got to be better at lying," Blake quipped.