FYI: Its very hard for someone to touch your urethra, its a hard place to reach.
But I see what you are trying to say. Even if he touched his penis with pre-cum and semen, and then touched your gential area (penis --im second guessing myself your male), you have NO risk for STDs.
Even if he touched my urethra??
...and then touch my penis*, sorry!
You can absolutely NOT get gonorhea or chlamydia "down there" from PERFORMING oral sex on someone. You can get it however orally; oral gonorrhea from giving oral sex is a low risk encounter
Hand-genital transmission is a NO risk encounter.