A Dog Ate My Homework/Playing With

Basic Trope: A student does not have his/her homework because a dog apparently ate it. Often, the teacher does not believe this excuse.
 * Straight: Bob's homework was eaten by his dog Tropey, but his teacher doesn't believe the story.
 * Exaggerated:
 * Tropey ate Bob's entire schoolbag and everything in it, along with several of Bob's other possessions.
 * Tropey ate Bob while he was doing his homework.
 * Downplayed:
 * Tropey chews on Bob's homework and spits it out, leaving it in no condition to be turned in.
 * Tropey ate half of Bob's homework, which means Bob gets an F for this assignment (but at least not a zero).
 * Justified:
 * Bob's homework was an edible assignment for cooking class, and he left it on the floor where Tropey could get to it.
 * Bob is a pathological liar and his teacher is justified in not believing him.
 * Bob often forgets to feed Tropey, so the poor dog eats random objects for sustenance.
 * Bob (or his mom) spilled bacon grease on the paper, and the dog gobbled it up for that reason.
 * Inverted:
 * Bob's biology homework eats Tropey.
 * Tropey does the homework for Bob.
 * Subverted:
 * Bob's homework disappears and he assumes it was Tropey, however, Bob had just carelessly misplaced it.
 * Or the teacher does believe him.
 * Double Subverted: However, as soon as Bob finds his homework, Tropey snatches it out of his hand and eats it.
 * Parodied: Bob is an anthropomorphic dog with a bad habit of eating his own homework.
 * Deconstructed:
 * Bob is faced with the dilemma of what to do with a neurotic, out-of-control dog that compulsively eats everything in sight. He even considers taking Tropey to the pound.
 * Tropey begins to suffer severe stomach trouble due to eating Bob's homework.
 * Reconstructed:
 * After the incident, Bob takes steps to help calm Tropey down, and keeps his homework out of reach at all times.
 * Bob manages to get Tropey to a vet in time. He gets better. Tropey remembers the incident and learns his lesson.
 * Zig Zagged: Tropey has occasionally been known to eat important documents, but at other times is very well-behaved. On the occasions where he does chew up homework, the teacher will sometimes believe it and sometimes won't. Furthermore, Bob has been known to lie to his teachers, so when he doesn't have his homework, it may or may not be Tropey's fault at all.
 * Averted: Tropey never eats Bob's homework, and Bob never has to make excuses.
 * Enforced: "Hmm, Bob has a cute dog that doesn't really do anything. I know, let's have an episode where the dog causes some trouble for once!"
 * Lampshaded: " 'A dog ate my homework, sir'. Oh man, that's the oldest excuse in the book! My teacher will never believe me!"
 * Invoked: Bob feeds his homework to Tropey on purpose.
 * Exploited: Bob takes advantage of his gullible teacher and uses this excuse even when Tropey doesn't eat his homework.
 * Defied: Bob doesn't let Tropey go anywhere near his homework, let alone eat it.
 * Discussed: "You ate my homework? Seriously? Out of all the things in here you could have eaten, you picked my assignment that's due tomorrow! BAD DOG, Tropey! BAD DOG!"
 * Conversed: "Oh, look. Bob just left his dog alone in the same room as those important documents. Three guesses what happens next."

Tropey! You bad dog! Did you eat the link back to A Dog Ate My Homework-oh no, wait, there it is... Sorry, boy.