system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do dogs love their bellies being rubbed?
gpt
A dog rolling on its back for you while you're petting it is usually a submissive gesture. The dog has complete trust in you and is relaxed while you are probably scratching an itch that he/she can't get at. Like the top of your head, there are nerve endings that make being scratched/pet feel good. This is why cats love to be pet and scratched as well.