Since there is no law against indoor prostitution in RI (search this forum for many supporting references for that info, but it's true) Asian Massage Parlors are all fairly friendly, assuming you are a gentleman.
You buy time at the door and negotiate personal tipping with your assigned massuse. Get addresses from the Providence Phoenix.

For the most return on your investment, get the whole massage first before negotiating the fun, 'cause once you pop you're out.

Check out the reviews under, RI, Providence, then Massage Parlors.  Its the wild wild west.