Garth Brooks and Trisha YearwoodGarth Brooks, who came out of retirement over the weekend to begin his five-year run performing in Las Vegas, also celebrated his fourth anniversary to wife, singer Trisha Yearwood. And while he has some of the world's finest restaurants at his disposal on the Vegas strip, he chose fast food to commemorate the occasion.

"That was our anniversary dinner," he says in PEOPLE, of their late-night McDonald's meal, adding that it wasn't his first choice. "We had a big night planned and at the last minute they moved the youngest one's Christmas carol program to that night. I promised them a big, fancy dinner, but we went and grabbed McDonald's fries and went home."

Looks like the rain check may have to wait. Garth is now busy performing at the Wynn, while his wife also recently performed in a holiday special, 'Christmas at Belmont,' set tol air on PBS. A graduate of the university, Trisha was accompanied by more than 400 voices from Belmont, as well as the Nashville Children's Choir.

"It's the holiday time, and you're in such an amazing place to see the excitement in their faces and to see that enthusiasm," she tells CMT. "That's what carries you through. I've been [performing professionally] for 18 years, but I still have that real enthusiasm. And I hope they get that -- that I'm having a great time. I'm having as much fun as they are. It always energizes me when you are with a group of people like this who really love what they're doing."

'Christmas at Belmont' airs on PBS Wednesday, Dec. 23.