First off, it's not a good idea to feed your dog un-sorted table scraps, for several reasons; doing so fosters begging, some foods are toxic to your dog, some meals are high in fat content, sugary foods and starches can cause cavities that are super expensive to fix and if your dog gets a tummy ache from the food you fed him... he can't yell at you.
That said, there are enormous benefits to foregoing bagged dog foods and putting puppy on an all natural diet of proteins, raw bones, vegetables, and starches. But that's a whole different chapter. For now, lets concentrate on foods that are bad for your dog.
1.) Cooked bones: They become brittle and can splinter, which means that your puppy is ingesting sharp flinty pieces that can damage the soft lining of the throat or puncture his stomach lining. Fish and chicken bones are especially bad.
There are cheap marrow bones available in the meat section of your supermarket. You can give those to puppy, raw of course and they're good for his teeth and they are indestructible.
2.) Raw eggs, chicken: Because of salmonella. If you can't resist giving puppy these things, cook them first.
3.) Candy, gum, soda, sugary foods: Dogs get cavities too, except tooth decay is exerbated by the fact that they don't have their teeth brushed every day. Also, sugary foods are fattening, and can lead to obesity, and diabetes. Plus, if your dog gets cavities, he can't tell you his teeth are hurting, and doggy dentists are super expensive and of course, dental visits are scary (well for me they are).
4.) Beer, alcohol: (DUH) This is not funny. Invariably some idiot will try to give your dog beer. Of course dogs like it, but it's bad for them. It can cause intoxication, coma and death, alcohol is a poison.
5.) Onions: Even what appears to be a small amount can kill them. Garlic cloves aren't very good either. I recommend avoiding things seasoned or cooked with onion powder as well.
7.) Grapes and raisins: They cause liver failure in dogs. Large and small quantities of both should be avoided.
8.) Mushrooms: Be careful of the ones that shoot up in your yard, they're often irresistible to dogs.
9.) Artificial sweetner: Xylotol is the ingredient to watch for. It's used in sugarless gums and candies, so avoid them.
10.) Macadamia nuts
Still curious? The Animal Control Poison Center's website: