pazZzurro: Depends on your friend's tastes I guess. Dogs don't have a lot of needs, with all due respect of course.
Here are some ideas for a great dog gift :)
1. Maybe a long and slow walk. Dogs love to be outside, and they feel very unsafe if you rush - a dog needs time to sniff everything, that is how they feel secure. If you don't give them enough time, they won't be enjoying the walk as much.
Then again it is autumn and if in Ukraine the weather is similar to what I see outside my window, it might be too cold for a Chihuahua (and they like when it's warm). So maybe buy/make him a sweater, so that he won't be cold in the coming winter?
2. Someone suggested a big bone. I would say you definitely should buy him a treat, but it's up to you and your friend to find the best one, that he is going to enjoy. A Chihuahua is a small dog and has rather small teeth, so a big bone might not be ideal - he may feel frustrated that it's either too hard or too big. Try to find him something he may like and can chew through and eat. The best way is to go with him to a pet shop that sells different dog foods. Better pet shop's allow their customers to enter with your friend and sometimes give free samples, so that a dog can choose what he wishes to get ;)
3. If your friend likes to take a bath, then maybe you could take him to a groomer? Some dogs like to be treated to a bath and have their hair groomed, others hate it. You probably already know if Sam likes it or not.
4. A great present is buying a new place for him to sleep. If the old one is dirty and smelly, it's a good thing both for you and your friend to buy a new one. He will probably have to adjust to it, so it might not be pleasing for him right from the start, but in time he will certainly like it. Alternatively you can buy a new bowl for food/water, or a new, soft collar.
5. Generally spend some time with him. Play games (fetching a ball, chewing on a rope), pet him, scratch his tummy. If you have the ability, take him for a trip to the countryside, where the both of you can run around free, and meet other dogs (check if they aren't agressive towards each other). That is a sure way to put a smile on Sam's face :)
These are the basic things... If I think of something more "unique" I will let you know.
Thanks for the cool suggestions. I'll answer in order:
1. I've been thinking about buying warm clothes too, as you correctly point out winter is coming. Sam is not very fond of the cold, so I always wear it under the jacket looks funny enough, but not comfortable. Well, he's comfortable and warm, but I'm not. So I like the option although I will search if I find something interesting by all means I will share
2. Bone is a good choice, but Sam is already so full of bone that I'm afraid he might get sick. Yes, and veterinarians do not approve as the bones have a bad effect on digestion.
3. Sam loves to bathe, my wife and I bought him a bath for that, he loves it very much and trying to take it away to wash it is a real tragedy. Sam is really starting to whine.
4. Sam has a warm soft place to sleep. Even though he shares it with a cat. But nevertheless, we'll have to change soon. Maybe next year.
5. We are planning to go to the sea next year, so thanks for the suggestion to buy a play toy. And so Sam has a cute squeaky yellow duck.
Thanks again for the great suggestions, but I'd be happy if you offer anything else)
darktjm: I haven't played it myself, but I think Saint's Row might be the sort of game you're looking for.
https://www.youtube.com/watch?v=a_z4IuxAqpE Sam should appreciate it. Since he likes shooters and chases. Every time he sees a car he gets excited, barks, and sometimes can howl.
Sam also loves chorus although he reacts ambiguously. At first, he is scared, but when you get away from the chase or get rid of evil spirits, he barks approvingly and proudly. That was when I played Resident Evil.