Your friend should remember that human toothpaste is designed to be rinsed and spat out, not swallowed, and I've not come across a dog yet that's been taught to do that! It's best to use a non-foaming one specially designed for dogs. :)
No, it's not ok. It can make people ill if too much is swallowed, let alone an animal it's not designed for. Have your friend find a doggie friendly toothpaste...easy to find. ;)