Todd Williamson/E! Entertainment
The country singer wished his girlfriend Gwen Stefani a happy birthday on Thursday with a sweet message, professing his love for the "Hollaback Singer" to his millions of Twitter followers.
"Happy birthday @gwenstefani!!!!" Shelton wrote. "I love you so much it's actually stupid… And possibly illegal in the state of California."
NBC got in on the birthday fun with a celebratory tweet of their own. The Voice's official Twitter wrote, "Wish @gwenstefani a happy birthday with your favorite Gwen GIF," prompting fans of the show to honor their favorite judge.
"Happy bday to this lovely lady that makes the show so much better just by being her adorable, funny and dorky self. Wishing u have the best day ever," one fan wrote, attaching a GIF from Stefani's epic Carpool Karaoke.