Eoin Macken On Working With Mrs. Obama, Dr. Biden & Trace Adkins in ‘The Night Shift’

Eoin Macken from ‘The Night Shift’ (NBC)

TC Callahan (Eoin Macken) and the men and women of San Antonio Memorial are about to get a special surprise on Monday’s “The Night Shift.”

First Lady Michelle Obama and Dr. Jill Biden will appear on the NBC show, airing at 10/9c after “The Voice.” In their appearance, they’ll play themselves, thanking the doctors and nurses (many of the character on the show are military) of the fictional hospital for helping veterans, and getting the word out about how veterans and their families can get help and counselling at vet centers. The women also recorded a PSA with “Night Shift” stars Eoin, Jill Flint and Robert Bailey Jr. for their Joining Forces initiative.

“I didn’t expect when I started doing this show that they’d send the Irish guy to Washington, to meet the First and Second ladies, so that was pretty cool,” Eoin told Access Hollywood. “It was quite an honor.”

The episode also features country music superstar Trace Adkins, who plays Colonel Elwood “Smalls” Green, the mixed martial arts group therapy leader, who has been helping Eoin’s character TC, with his PTSD. Smalls is the one who introduces a special message from Mrs. Obama and Mrs. Biden in the show, and it meant that the two had to act on the series. It was “ER” alum Eric La Salle, a director for “The Night Shift,” who gave the women tips on how to deliver their performances.

“Eric La Salle is a character and you’ve got to give the guy credit because he just owned the room and Michelle Obama, she’s an incredibly charismatic person. When she comes in, she just has this amazing presence and she’s so sweet and charming and funny and she really was lovely and then Eric… he has his little favorite phrase, which is when we’re acting, he likes to get people to not act and… his phrase is, ‘put some stank on it.’ It’s his catchphrase way of saying, ‘make it dirty,’ so you’re not saying the lines, you’re just doing it. It’s his way of just making the acting natural, and he said that to Michelle Obama and Jill Biden, and we were like, ‘What?’ He just coached them through it and they had fun,” Eoin said.

In addition to meeting Mrs. Obama and Mrs. Biden for the episode, the women, some of the cast and producers visited Silver Spring Vet Center in Silver Spring, Md., to meet with the facility’s clients, staff and medical personnel.

The whole experience was something Eoin couldn’t help but write home about.

“[I] put something up on Facebook [and] everyone’s like, ‘What the… ,’ and I’m like ‘Yeah, just casually meeting the First Lady.’ They’re like, ‘Wow. Why?’ I’m like, ‘No big deal.’ That’s been one of the more enjoyable Facebook posts I’ve got to ever put up because I don’t really do it that often, but I’m like, ‘This is worth it,'” he said.

Filming the episode was also a big deal on the Albuquerque, New Mexico set because of Trace’s cameo, and it gave the Irishman a lesson in country music.

PHOTOS: ‘The Night Shift’ Season 2

“I realized how important he was, how big he was, how popular he was because pretty much everyone on set wanted to talk to him and all of a sudden you had people coming down from the office and so forth who were suddenly hanging out on set that day and I was like, ‘What are you doing here? You’re in accounting. You never come down to set.’ And they’re like, ‘Oh, you know, [I] thought I’d check out what’s going on,'” Eoin said.

Since Trace is such a tall man (he’s 6’6″), Eoin revealed that their director, Eric, had to find a way to make the country star a little shorter on screen.

“He was wearing these big cowboy boots. Eric was like, ‘Dude you can’t wear these cowboys boots.’ He had to take off his cowboy boots, so in the scenes he’s doing, he’s doing it in his socks,” Eoin revealed.

And if the episode isn’t big enough, it also includes Wendell Pierce as a patient.

“This is actually a pretty intense episode now you start bringing that up. Wendell Pierce is awesome,” he said.

“When you get to work with someone like Wendell or like someone who can really, really f**ing act, it’s just a pleasure. It really was, and it just makes it easy, because a lot of acting for me is just about reacting and watching the other person and listening. So when you’ve got someone like Wendell, it just makes it easy,” Eoin said. “He was great, but my buddy was over from Ireland for the week and he’s a huge fan of ‘The Wire,’ so he was having a massive kick out of it. … He was like, ‘This is the best week ever.'”

“The Night Shift” airs Mondays at 10/9c on NBC.

— Jolie Lash