SMUG: adjective; Facial clue indicating undiscovered intentional mischief which will most undoubtedly be unpleasant in nature for humans. (Demonstrated by Sammie Poochon)

"Oh yeah, sure, the TP roll is doing just fine... *snicker*"
GLOWER: noun; Often successful occular device employed by canines to manipulate or influence their humans in order to obtain any and every earthly thing. (Demonstrated by Lord Pippin)

"Come on, don't you want the best for me? Now, move over, the king-sized bed is mine..."
INNOCENCE: noun; Implied and most often fictitious state demonstrated by wide-eyed and blank stares, used as a defense mechanism once a disaster has been uncovered. (Illustrated by Cokenee)
"Nope, I didn't do it. See how big my eyes are? Are you buying it yet? Maybe if I prop by eyelids open with toothpicks..."