So you can do what with them?
Just this or other things?

There are a numer of resoucres on the Internet that may be of help depending on what you are trying to acheive.

A basic CBT - "cock and ball torture" guide can be found here:

Mistress Ariachne's BDSM Workshop: Cock and Ball Torture
http://bondage.com/id/12/which/152/show_column.html

Extreme restraints has a nice article on cock rings:
http://www.extremerestraints.com/art...k-rings_5.html

There's even a book called "Ways to Play with the Family Jewels" by Hardy Haberman

This is a link to a review:
http://alt.com/intgroups/aa188/tyadm...n_article.html