With a spa party on the mind I had lots of fun looking up soap products on Etsy.
Here are a few I thought were pretty clever:

Fish in a BAG Soaps from Carolina Soap Lady
Chips and Cheese Fun FOod Soaps from AJ’s Sweet Soap’s (such a clever name too!).
Popcorn Soap from Howard’s Home’s.
Skull Soap with KC Soaps n’ More.
There are so many other fun soaps – just go to Etsy and search for Novelty Soaps.  You are sure to be amazed!