On Thursday's episode of the late-night talk show, Krasinski appeared as Colbert's first live, in-person guest in 14 months -- and hilarity ensued. The two -- who were joined by Colbert's wife, Evie, -- covered several topics, including Krasinski's new film "A Quiet Place: Part II" and quarantine food cravings.
However, at one point, Colbert, 57, wanted to find out just how "strong" his guest really is and challenged the 41-year-actor to an arm wrestling match.
"I want you to know, I'm just looking at the guns [and] I'm like, 'Hey man!'" Colbert told Krasinski, who quipped, "The key is you buy things at Baby Gap and people are like, 'You're huge!'"
After they figured out the correct arm placement, Colbert prefaced, "I want you to know, this is not personal."
The two then began the arm wrestling match -- and right off the bat, it looked like Krasinski was already winning.
"You're very strong," the "Jack Ryan" star teased, to which Colbert replied, "You're younger, you're strong, but I'm old and wily."
"I didn't know we were really doing it," Krasinski said, bursting into laughter.
A few short moments later, the "Office" alum won the match and Colbert said Krasinski "didn't even try."
Krasinski denied it, saying, "It was so much fun! I did try, absolutely."
"Then how come you look like that and I look like this?" asked Colbert, who was catching his breath.
Krasinski appeared on "The Late Show" to promote his new film "A Quiet Place: Part II," which was originally set to be released in March 2020, but was delayed several times amid the coronavirus pandemic. Krasinski previously stopped by the late-night show to promote the film ahead of its first postponement back in March 2020 -- only a couple of days before Covid-19 was officially declared a pandemic.
On Thursday's episode of "The Late Show," Krasinski and Colbert discussed the hilariously awkward hug they shared when they were last together over a year prior.
"You can get a sense that we were beginning to understand that something bad was about to be coming down the pipe, we weren't quite sure," Colbert said, showing the clip of Krasinki's entrance from his last appearance on the show.
"Just before I went out, somebody was like, 'You're not going to touch him, are you?'" Krasinski revealed. "And then they were like, 'And John Krasinski!' And I was like, 'Am I not supposed to?!'"
Colbert admitted to Krasinski he hadn't actually watched "A Quiet Place: Part II" although he told him he had at the time. However, 14 months later, the late-night host has since seen the film and praised the movie for being both "a deeply moving human story" and a horror flick.
When Colbert asked Kraskinski how he was able to achieve that, he brought up a conversation he had with "The Office" creator, Greg Daniels, many years ago.
"I actually learned that lesson from Greg Daniels on 'The Office,'" Krasinski recalled. "It was like three weeks into shooting and I was so nervous for this scene and he said, 'Can I ask you a question? Are you OK?' and I said, 'Yes, this is my favorite joke in the script, I want to make sure I deliver it really funny.'"
"He said, 'Whoa, whoa, whoa. You don't deliver anything funny. You just deliver it and let people decided whether it's funny or not,'" he continued. "And he said, 'You just do the character and if they fall in love with you, they'll go on any ride.'"
The "It's Complicated" star added, "I literally thought of him when they said direct a horror movie. I was like, 'I don't know how to do a horror movie.' So, instead, I just did a family drama and Trojan horsed it as a horror movie because I thought you'll be more scared if you fall in love with these characters."
Meanwhile, Krasinski -- who shares daughters Hazel, 7, and Violet, 4, with wife Emily Blunt -- later revealed that he, like many people, "indulged" during quarantine.
"I know you're all 'Jack Ryan' like hard now, did you lose it?" Colbert asked. "Did you bloat up?"
"Oh yeah. There was a moment there where we were still going to shoot, and I said, 'I am totally ready to shoot. We just need to change the name of the show to 'Fat Ryan,'" Krasinski quipped. "And then, let's do it.'"
The star said that he got "addicted to popcorn" -- and it reached a point that Blunt eventually intervened.
"My kids had microwave movie popcorn for something and they loved it and then just slowly the time started getting earlier and earlier," Krasinski told Colbert. "And at like 9:00 a.m. at breakfast, I was like, 'Does anybody want popcorn?'"
"And Emily was like, 'You gotta cool it on the popcorn! You got to stop microwaving popcorn at 9:00 a.m.'"
Also during the show, Kraskinski took "The Colbert Questionert" and revealed some fun facts about himself, including his favorite action movie, whether or not he's ever asked someone for an autograph and the one clothing item he really needs to throw out.