Semen in man's rectum?

OK, healthy sperm from a healthy man will not cause any harm being in a man's anus or rectum. But the sex to plant it deep in there can be harmless or it can rub to much and damage the inner rectum lining tissues since these are much more delicate than vaginal tissues. Vaginal tissues are designed to be much stronger for sexual intercourse and are designed to be stimulated during sex. Gentle anal sex between healthy men isn't likely to cause any harm. Rough anal sex can cause anal tissue to break and bleed. So having anal sex between two healthy people can still be risky for bleeding and anal tissue rips. Any diseased sperm anywhere inside a man and especially inside his rectum can cause diseases for the man receiving the infected sperm inside of his body from sexual acts. The man injecting that sperm can catch diseases from an infected man's rectum. Anal sex is one of the highest risk activities for catching HIV if either of the two sex partners have HIV to spread to the other man. If neither has any HIV, then they cannot spread HIV by anal sex.