Of you haven't heard of a Dental Dam, its a thin sheet of Latex that can be used as a barrier for oral sex.
Many people use Saran Wrap (that plastic clingy wrap you get at the supermarket) instead.
Question is...have you practiced safe oral sex? If so, how? Have you tried dental dams? Would you consider using them? Would you be offended if someone used it on you?
Its supposed to protect you from contracting STDs.