Tina,
Good question. If you have a small hand you will be able to squeeze in and the Orangutan's mouth (even on the small one) is easy to move. The Chimpanzee has a smaller mouth. The gorilla is easy also in the small versions.
However with that said, you might find the Medium or Large a more professional size. But then the babies have those wild surfer shorts on.....decisions, decisions.....(this is why we put up the "Thinker" on our products page!
http://www.axtell.com/products.html
Ax