A lot of people talk about so-called "semen retention", but that does not and cannot exist, since semen is only produced when we are about to ejaculate. In other words, there is no semen in our bodies stored away that gets "absorbed" every now and then. Quick recap of how an ejaculation occurs: sperm cells produced in our testicles are carried to the epididymis (structures located near the testicles for cell maturation) and then through the vas deferens (long tubes) they go to the prostate. Once inside the prostate (which is behind the urinary bladder), the sperm cells receive the contents from the seminal vesicles (of which we have two on top of the prostate); this content is mainly mucus and some glucose, which will give the cells energy to travel the last part of their journey when they try to fertilize the female egg. About 95% of the ejaculate is mucus and a tiny percentage is composed of sperm cells. Since "semen" is the content of the ejaculate (sperm cells + mucus + glucose), so-called "semen retention" does not exist.