His lips are sealed! Ryan Reynolds and Blake Lively have chosen not to reveal the name of their 1-month-old baby daughter, but that didn't stop David Letterman from trying to guess it when the Mississippi Grind actor stopped by the Late Show on Wednesday, Feb. 4. 

"We definitely [have a name]," Reynolds, 38, assured the host. Joking, he added, "I threw out the idea of just never naming the kid to be totally original, but we have a name. I just don't want to say it in, like, a media context. I tell everyone who I meet, so it'll come out."

Letterman proceeded to grill the first-time father for clues, asking whether it's a family name (it is), Lively's mother's name (it's not), and/or a biblical name ("maybe kind of, yeah"). He also offered several seemingly random guesses — among them, Olivia, Sophia, Emma, Eva, Isabella, Abigail, and Ruth.

"I should've worn my cup. I didn't know I was gonna get busted this hard!" the actor, next starring in The Voices, quipped of the late-night comedian's incessant guessing.

Letterman eventually gave up, and the two moved on to another subject: Reynolds' stunning wife.

"It's amazing," he gushed of life with his new family. "I'm not one for vomiting declarations of sentiment out across the airwaves, but when we had that baby, I fell more in love with my wife than I'd ever been in my entire life. I couldn't even believe it."

Even more incredible, though, is how much he loves his daughter. "I used to say to [Blake], 'I would take a bullet for you. I could never love anything as much as I love you.' I would say that to my wife," he told Letterman. "And the second I looked in that baby's eyes, I knew in that exact moment that if we were ever under attack, I would use my wife as a human shield to protect that baby."

That's not all Lively's good for, of course. "[As] the guy, I'm just like a diaper-changing facility hooked up to a life-support system. But my wife, she's breakfast, lunch, and dinner," Reynolds joked of Gossip Girl alum Lively. "She's a human Denny's, all day long and all night long. Romantic right? She's the most beautiful Denny's you've ever seen, though."