Never share chocolate, xylitol, grapes, onions, or alcohol — call a vet if ingested.

Chocolate, grapes, raisins, onions, garlic, xylitol (in sugar-free gum), and alcohol are common household toxins for dogs and cats.
Keep counters clear and teach guests not to feed table scraps. Even small amounts of some foods can cause serious illness.
If your pet eats something toxic, note the product and amount, then contact a vet or poison hotline immediately. Do not wait for symptoms.