Simmons had been a frequent visitor to Letterman's late night programs over the years, making a total of 35 guest appearances.
During his visits, Letterman would often tease Simmons about his shorts or exuberant behavior, and Simmons would react with a playful pout and turn to the audience for sympathy.
Letterman promptly hosed him down with a fire extinguisher.
Simmons is currently on "a personal crusade to bring fitness back to the public school system." He has posted a survey on his Web site and invited parents, teachers, and school administrators to answer questions about the state of their school's physical education program.
"I plan to compile the information I receive and take it to Washington to share with the only people who can make the needed changes: the men and women in our government," Simmons writes on his site.
He's also promoting a new electric tabletop steam cooker called Steam Heat.