Justin Hartley probably won’t be doing any dog-sitting any time soon. On The Tonight Show Starring Jimmy Fallon, Wednesday, the This Is Us actor, 41, recalled to Fallon how watching a friend’s pet in college led to a woman pulling a gun on him When Hartley was a student in Southern Illinois, he watched a friend’s white German Shepherd while the pal was honeymooning “Their dog was like their baby,” Hartley explained. “I had a dog at the time. It was this little beagle I was like, ‘Yeah, bring the dog in. No problem.’ “ Unfortunately, during the pooch’s stay, the German Shepherd escaped through Hartley’s window — which was left open because his beagle could not jump through it “The dog takes off through the window. I spent two days tracking this dog down,” Hartley remembered “I lost like 15 pounds. I was running all over the place. It was unbelievable.” He had to be creative when the newlyweds phoned to check in “They called me like three or four times a day to check on their dog, and I always had an excuse,” Hartley said “I was pretending to be the dog. I was making noises. They were like, ‘He sounds weird ’ I was like, ‘Well he’s really tired. He went on a long walk. He’s exhausted.’ “ Hartley eventually located the dog across town “I found him all the way on the other side of Carbondale in this woman’s backyard I went into her backyard, and I cornered the dog. The dog was kind of spooked,” Hartley explained “She comes out with a cordless phone with an antenna and a gun. I was like, ‘Ma’am ’ … I was like, ‘That’s a dog’ and explained.” “So you and the dog are both spooked,” Fallon said “That should be a movie.” That movie would end with a bit of irony: Hartley had locked himself out of the house, and when he returned with the dog, he had to “break in through the window that he had opened ” This Is Us airs Tuesdays at 9 p.m. ET on NBC.