"John and Emily, not only are my wife and I very good friends with them, they're our neighbors," Kimmel told Monday night's Jimmy Kimmel Live! audience. "We live right across the street from each other. We have a holiday tradition that was started by them a few years back."
Apparently, the tradition began three years ago and just seems to get more elaborate as the years go on.
Kimmel gave a rundown on past pranks and then shared what the cute couple have been up to this year.
As he tells it, late one evening after he finished taping a show, Kimmel left the studio and went out to his car to find it all wrapped up like a Christmas present. As he tore the paper off the car, he found that it was filled with ornaments, which ended up all over the parking lot when he opened the door.
— Harper's Bazaar (@harpersbazaarus) December 17, 2014
"I have to hand it to you, that is very impressive," Kimmel told Blunt.
"It was a combination of the two of us. We went through a couple of options and decided just to do all of them," she explained.
The same thing happened the next night, but this time, when he unwrapped his car, a band of Christmas carolers got out of the car, singing Hark! the Herald Angels Sing, and a reindeer strolled up to say hello.
"Not only were you terrified and I love that you flinched because that was the best bit ever, but it is your nightmare of people singing at you," the Into the Woods actress said.
"When I saw the reindeer, I wasn't entirely sure they exist, so I inspected it to see if you'd attached horns to some other kind of a deer," Jimmy admitted.
Blunt and Krasinski had one more prank planned for their friend — a live prank on Monday's show.
"I don't think we can stop at that, so I just want to take a quick look live at your car," Blunt said.
— VANITY FAIR (@VanityFair) December 16, 2014
When the cameras turned to the parking lot, Krasinski was seen dressed in a Santa suit standing beside Kimmel's wrapped car. The pranksters had enlisted the help of Kimmel's wife Molly to collect his personal items, including his laptop, to give away to passersby. After the gift distribution, Krasinski drives off, but crashes the car several times before he stops. And it was then that a piano fell from the sky onto the car. The last view is of the Office alum staggering out of the driver's seat.
"I don't know where we stop, though," Blunt said once the cameras turned back on the host. "I don't know how we ever put a cap on this. We've got to keep doing it."