Look sweetheart, you can shove all the metal you want into your body. As long as you don't try to shank me with a toothbrush during some weird prison sex fantasy while I'm trying to play Wii Golf, then we will be just fine. =)
I have had oral from a woman with a tongue barbell and many different attachments. Didn't do anything extra but when the barbell was cold, the sensation was unusual. I'm not a guy who's that into receiving oral though so this may not help as much.