She's too smart for my own good

I snuck a handful of M&M's this afternoon and a few minutes later Abigail comes up to me.  "Look at your mouth," she says and I quickly open and shut it trying to humor her.  She persists, "Open your mouth."  So I grudgingly let her look in my mouth.  She then exclaims, "It's all yucky."  She pauses for a second, contemplating what this means.  "Oh!  M&M's!"

Caught brown-toothed by a three year old.