My puppy keeps peeing on my bed. Why is this one of his favorite activities?
As many pup owners have learned, peeing is a way for dogs to mark their territories, which can include your bed, unfortunately. In the wild, a dog would try to throw predators off from finding them by covering the predator's scent with his own pee. This is most likely why puppies pee on your comforter: because it smells like you.
There are other reasons why dogs will sometimes do this. Dogs pee when they are stressed, excited, or scared. It's a way for them to let you know you're the boss and that they're submitting to you. (Ask a Dog Trainer)