On the most recent episode of Shepard's "Armchair Expert" podcast, the couple revealed that their daughters Lincoln, 8, and Delta, 7, sleep with them in their bedroom and recalled a gross mishap that took place in the room.
"You know the girls sleep on the floor of our bedroom," the 41-year-old actress said and shared that the family watches "How It's Made" before they go to bed.
One night, Bell noted that she had started to "smell a really raunchy smell" which had been lingering for a few days prior.
"She was sitting there, and we were getting the paperwork or whatever," the actress shared with Kimmel. "And she looks up at my doctor with this sly look—because you can only see your eyes through the mask—and she said, 'Are you the doctor who's going up my mom's butt?'"
The doctor confirmed Lincoln's question and asked if he should look for anything particular "when I'm up there" to which the 8-year-old hilariously stated, "The rubber nut."
Bell elaborated that "the rubber nut" is a reference to a phrase Kristen and Dax use whenever they can't find a misplaced item.
"We say 'up your butt with a rubber nut' in our household if you're missing something," she laughed. "It's a thing in our household, if you're like... where are my shoes? 'Up your butt with a rubber nut!'"