There are several possible reasons why a dog may lick a person’s belly button.

1. Grooming: Licking is a common grooming behavior in dogs, and they may lick their own bodies as well as the bodies of other dogs or humans. Dogs have scent glands in their mouths that release pheromones when they lick, which may be a way for them to mark their territory or communicate with others. Dogs may also lick as a way to clean themselves or remove dirt or debris from their fur.
2. Attention seeking: Dogs may also lick their owners as a way to seek attention or affection. Some dogs may lick their owners excessively when they are feeling anxious or stressed, as a way to self-soothe.
3. Taste: It is also possible that your dog is simply interested in the taste of your belly button. Dogs have a strong sense of smell and taste, and they may be drawn to the scent of your skin or any lotions or soaps you use.

While it is generally not harmful for a dog to lick a person’s belly button, excessive licking can lead to irritation or infection. If your dog is excessively licking your belly button or other areas of your body, it is important to speak with a veterinarian or a professional dog trainer to determine the cause and address any underlying behavior issues.

In conclusion, there are several possible reasons why a dog may lick a person’s belly button, including grooming, attention seeking, and taste. While it is generally not harmful for a dog to lick a person’s belly button, excessive licking can lead to irritation or infection. If your dog is excessively licking your belly button or other areas of your body, it is important to speak with a veterinarian or a professional dog trainer to determine the cause and address any underlying behavior issues.