What is the math joke that goes "what happens to a dog who eats table scraps"?

The second half of the joke, "what happens to a dog who eats table scraps," is that "it gets splinters in its tongue." But, just as bits of a wooden table are unsafe for dogs to eat, so are several common foods.

Most dog owners are aware of the toxicity of chocolate in their furry friends, but they may not know that grapes, raisins, onions, caffeine, macadamia nuts, xylitol, alcohol, uncooked yeast dough, and fruit seeds and pits all pose significant health risks. Thus, it is important to read all product labels before giving in to the puppy-dog eyes begging for table food.