Dave is a cat with many passions: food, naps, exploring, guarding the home, head rubs, traveling the world, eating food, and many others. One thing that Dave is not too crazy about is having his belly rubbed.
When someone rubs Dave's belly, sometimes Dave likes it, sometimes he merely allows it, and sometimes he lashes out against the person responsible for the ill-fated attempt to rub his belly.
The third category of potential outcomes has led to a system wherein potential belly-rubbers know they shouldn't use their hands to rub Dave's belly. A socked foot, however, is the perfect belly-rub tool, protecting the belly-rubber from any explosive response from Dave.