Partialism is like having a favorite toy. You know how you have that one toy that you play with a lot? Well, some grown-ups have a favorite body part that they really like. It could be something like feet, hands or their hair. They might like it so much that they want to touch it, smell it or kiss it.
Just like how you might like your toy more than your other toys, some grown-ups like one body part more than other parts. This is okay as long as everyone involved is happy and comfortable with what is going on. It's important to remember that not everyone likes the same things and that's okay too.