I've heard the phrase "she's a spinner" used here.  Could someone clarify what that means?

A spinner is a petite and relative thin gal.  Usually under 5'2" or 100#, they are referred to as "spinners" because of the fantasy (or dare I say the reality) of being able to mount them on your manhood and spin them around.

of her spinning around like a top lol Maybe wrong image?

In Korea and Thailand, and God I wish everywhere, you can have a woman sit in a hanging basket called appropriately enough a "Bangkok Basket".  They wind her up, lower her onto you, and let her gooooooooooooo!!!  OH!!! MY!!! G-I'm done.

I don't know why ... but in college campuses and backed up by some Internet slang research ....

A 'spinner'  is what WE used to call an "airhead"