You can teach a dog to tickle a person. It requires patience and a lot of positive reinforcement. Start by having your dog sit as you pet him. Coax him to reach out and touch you. Praise him each time he touches you. With time, he'll learn to touch you when you ask him to do so. Make sure that your dog is comfortable with the sound of your voice. You might want to reward him with a treat each time he touches you.