While speaking about his desire to "protect the lawn" from his 10-year-old daughter's budding equestrian career, Ellen brought up that Mark's dog, Champ, would be more likely to destroy his precious grass.
"No, he's this big," said the actor, as an image of the adorable pup took over the screen. "That was one of the things when I saw the guy who had the Pomeranian, I was like, 'Oh, how big does that dog get?' And he said, 'This is full grown.' And I said, 'How big is the poop?' He said, 'It's like a little Tootsie Roll.' And I said, 'Alright, I can manage that.' So I agreed to then get the dog."
Yes, he agreed to get the dog -- without his wife's knowledge. What could go wrong?
"Something very important, or someone very important, was coming to the house," the actor recalled telling three of the four of his brood, noting he did tell his oldest son the truth because he had to leave for track practice.
"So I told the other kids, 'Somebody important's coming,'" Mark explained. "Meanwhile, I'm in a meeting with my wife. She barges in the meeting and goes, 'I need to talk to you right now.' Drags me outside and goes, 'Why is Kim Kardashian and Kanye West coming here at dinnertime?' I said, 'What are you talking about?'"
Mark said his wife informed him that their youngest two, Brendan and Grace, told her about their dad's special guest and said to her, "If it's somebody important, it's got to be them!"
"So I'm like, 'It's not them! It's not them. I got a dog,'" he recalled telling his wife, who then "got upset because I didn't include her in the selecting of the dog and everything else."
After pestering Mark about what kind of dog he picked out, Rhea informed her husband that she hates "those little furry dogs."
"She was so upset, so I said, 'Okay, we'll tell the kids they can't have the dog when it comes in 5 minutes,'" Mark said he replied. "So she's sitting there, waiting by the door. And I mean, I knew I was in trouble. The woman comes in, lays down the crate, she opens the gate. Champ walks out, and my wife dives on the ground and says, 'Oh, my God! This is the most beautiful dog I've ever seen!' She starts choking the dog, like, won't let the kids see the dog or hold the dog. I'll have to send you those pictures."
"But thankfully, she and everybody's in love with the dog," he added. "But the dog runs the house." (Are you even a dog owner if your dog doesn't run your house?)
"You can't walk around without it barking in the morning or at night," he said. "So we're now all having to go to training ourselves to deal with the dog! But you know what, the smiles on their faces were absolutely precious. Best thing I ever did."
Mark told Ellen Champ "thinks he's a Rottweiler" and that his kids are already trying to make him famous. They've even created him an Instagram account: @champeranian. His first post was made just last month, and he's already got 28,600 followers.