I went through a phase where I never brushed my teeth ever for months on end. I do not know how this escaped notice.

EDIT: I should clarify that it was at a time when my mom was sick for a few months and she let me stay up late to make up for doing so much extra work. It started with not wanting to run water at late hours and wake her up, and then became habit.

Still, my breath HAD to have stunk.