. One surprising piece of information about the big day was that , who starred on The Newsroom with Munn, was the one who officiated the ceremony.

"[He] once said to Olivia if you ever get married, I'll perform the ceremony," he recalled. After Kimmel asked why the veteran actor said that, Mulaney shared his own take, "I think it was chit chat. But you take people up on what they offer..."

Mulaney also explained how his and Munn's son , now 3, hilariously stole the spotlight in the middle of the ceremony in the most toddler way possible.

"And he actually went to the bathroom in his diaper during it and announced it mid-vows," he said. "Yeah, a very sweaty, little 2 year old in a tuxedo just went, 'I'm pooping.'"

When Kimmel joked that it was great the little one made the announcement "while it was happening and not before or after," Mulaney quipped back, "Well, it's really an in-the-moment kind of declaration."

Last year also held another big milestone for the couple as he and the X-Men: Apocalypse actress also welcomed their second child together, daughter , via surrogate in September.