The term implies that she can sit on top of your cock and rotate around 360 degrees.

I'm going to be in Boston the 26th & 27th -- and would like to enjoy the best spinner in town?

You could check out some of the reputable local agencies.  Boston International, The Bella Donna and Room Service Girls are among the best for in-call.  After Dark is a good option for out-call.  They all have girls who fit your preference.  It just depends whether or not the girls you would like to meet are actually working that weekend.

The Bella Donna: http://www.thebelladonna.com

Boston International: http://www.bostonintescorts.com

Room Service Girls: http://roomservicegirls.com

After Dark: http://afterdarkescorts.net  

Have fun,

DJ

what exactly is a spinner?