It's wrong to lick your dog's eyeball because it's gross.
Stan is playing truth or dare with a group of friends at his house while watching his dog.
Stan wants to impress his friends.
Stan picks truth instead of dare and tells a very personal story.
Stan's friend laughs out loud and dares him to lick his dog's eyeball.
Stan's friends respect his bravery and courage to speak out in such a personal manner.
Stan agrees and in the middle of it, his mother walks in sees and yells at him.