Dale Irby of Garland, Texas, did not mean to start a 40-year tradition when he wore a coffee-colored wool sweater vest over a polyester shirt for a yearbook photo in 1973.

The first-year teacher, now 63, simply pulled the in-fashion-at-the-time clothing from his closet on picture day. Then the next year, his second as a teacher in the Dallas Independent School District, he did it again, by chance.

"When I got the pictures back the second year I saw that I had inadvertently worn the same shirt and vest," Irby told ABCNews.com. "It was a little bit embarrassing."

When it came time to take his third yearbook photo as a faculty member, Irby was married to his wife, Cathy, a fellow teacher, who dared him to wear the same outfit again.

"She said, 'Oh, just wear it again. Get three pictures and we'll get a laugh out of it,'" Irby recalled. "Three turned into five, and then five turned into 10 and I thought, 'Why stop?'"

Irby didn't stop wearing the sweater vest and shirt on school picture day 20 years, 30 years or even after having two children and moving to a new school district and a new school.

Last October, Irby wore the same sweater vest and shirt, both of which still fit, he notes, for his 40 th and final school picture. Irby retired at the end of this school year after 40 years, the last 18 as a physical education teacher at Prestonwood Elementary School.

His retirement was noted by his local newspaper, the Dallas Morning News, as ending, "one last echo of disco fashion."

"I don't have plans for it," he said of his famous shirt. "I do know the Smithsonian collects lots of things but I don't think they'd want it."

Irby said his yearbook outfit became a joke among his family - Cathy and their two children, Matthew and Sara - that he saw no reason to end. As the years progressed, he would change into the shirt for the yearbook photo and then change out of it immediately after.

"It became old enough that having it cleaned would make it fall apart," he said. "It really wasn't stylish and, to tell you the truth, it was a little bit tighter in the latter years than it was in the beginning. But I could still wear it and button it."

Irby's sweater and shirt were worn on him 40 times but the outfit got a second life thanks to his daughter, Sara, a kindergarten teacher.

"She asked if she could borrow it and I said yes and she took her school picture with it," Irby said. "My wife said, 'No, you're not doing that,' but it got a 41 st picture."

Sara was also responsible for bringing the sweater vest and shirt back to life for Irby's retirement party. She created buttons out of the 40 photos of her dad in the outfit and also created a life-size cardboard cutout of one of the pictures, with Irby's head cut out so that guests could insert theirs.

"Everyone I know now has pictures of their face with the sweater," Irby said.

The 40 pictures of Irby in his sweater are still kept in the same place he put each new picture each year, in one of his dresser drawers. While he said the 40-year tradition that surprised even him was fun, Irby doesn't think it will happen again.

"I doubt that I'll wear it again, even in a dare," Irby said.