Why does your dog stand on your foot?

I've known many dogs who do this. I believe it to be a sign of submission, greeting, or just happiness.

Dogs do this naturally and are usually smiling and wiggling when it happens. If they aren't smiling when they do it, I might be concerned, but I haven't see a dog yet that wasn't smiling. If you love dogs and are honored to be important enough to be greeted this way, a quick hand wipe will clean up everything. If you can't stand it, just discourage it like you would any other behavior.