First of all, outside of a long term relationship where their is reasonable suspicion of monogamy I DO NOT recommend the ingestion of body fluids, nakadashi or any other practices that involve receiving another persons body fluids.
That having been said, this was actually a concern that I had not heard before which was not a completely invalid concern.
Doing a very small amount of research I would have to say that with MOST mainstream recreational drugs the concentration would be low enough to not show up on a drug test.
That having been said, if the person is using drugs that you are having sex with the and you don't the chances of infidelity are somewhat higher, the values are different and should dump them before you accidentally have kids with them (yes I know this an oral sex question) or they infect you with an STD while you have unprotected sex with them.
butch12: no, i've never heard of this happening. rec. drugs go thru your blood stream, causing you to have a positive drug test...sperm or *** does not absorb into the blood stream. your partner's acidic juices from the stomach will break down and kill the sperm.
Actually this question was regarding oral sex which usually does not result in anything that has been received coming out of the genitals. The female urinary tract also does not, barring some rather bizarre and esoteric sex practices ever have sperm or for that matter any other item of male origination within it.
NO. When a woman recieves sperm, it goes in the urinary tract, and usually a bit comes back out when she stands up. It never goes in her system, so basically the next time she pees, it'll all be gone. Hope I helped!