WRONG!!
Most STIs are passed (or transmitted) between sexual partners through unprotected oral, vaginal or anal sex. Some STIs are passed by skin-to-skin contact. Using condoms and other barriers for vaginal, oral and anal sex is a good way to lower the chances of passing many STIs. If you hobby then you will always be taking a chance. Just because you do not have unprotected sex does not mean that you are good. If you are worried then quit the hobby.
This is a good link for info on STIs.
Sexually Transmitted Infections (STIs)