1. A travel guide: Dudu can give a friend a guide to introduce tourist attractions and delicious food in various places, so as to help friends better plan their travel itinerary.

2. A postcard: Dudu can personally write down the words of blessing and send them to friends, so that friends can receive Dudu's greetings during the trip.

3. A bottle of local special food or drink: Dudu can choose local special food or drink and let friends taste the local food culture.

4. A souvenir: Dudu can buy a local souvenir, such as a small sculpture, a key chain or a T-shirt, as a souvenir for a friend.

5. An interesting travel story book: Dudu can give a friend a story book about travel, so that a friend can have a pleasant reading on the trip.