The Great Believers by Rebecca Makkai:
“No, Yale, really, why did I pack this? I’m never flossing again.”
“Sure you are.”
“I’m telling you that I have decided not to. Like, right now. I’ve hated it my whole life, and what’s gonna happen to my gums in the next six months?”
“You’ve got much longer than that.”
“You think any dentist is even treating me again? I’ve got no dentist to yell at me! I’m never going in for another cleaning! I could eat s’mores for dinner every night and not brush my teeth.” He dropped the dental floss on Yale’s lap and grabbed his shoulders. “Ten-year-old me would love this.” And then he collapsed in frantic laughter that Yale couldn’t manage to join.