Has anyone ever contracted SDT from a clean-looking penis through oral sex?

Hi I am a bisexual, discovering my sexuality, and I am craving for some oral action, do and receive. I have this buddy I have been talking too and I want to perform on him, I know he receives from other guys.I know that there are risks involved and all, but seriously, has anyone EVER contracted anything through oral sex solely? He is super clean looking.Thanks a lot.