A man can be sterile if he has a congenital defect that causes sterility or if he chooses to become sterile through surgery including a vasectomy. He might also be sterile if he has suffered trauma or disease that destroys the testicles.
It is not advised for a guy to attempt to sterilize himself. There are numerous things like wearing tight clothing which can lower sperm count but sterilization should be done by a doctor.
Depending on your age, a man can get a vasectomy and a woman could get her tubes tied.
Sterility in males can be caused by disease or by radiation
It depends on why the man is sterile. There are many causes. If he has had a vasectomy, an operation to make him sterile, that operation can now be reversed for a majority of men, if they want to go through the hassle and expense. If a man is sterile for some other reason, there are many possible medical reasons and many possible treatments. Only a fertility expert knows all about it.
No this will not make him sterile.
Practice to not make a fool of yourself.
No but they will make his bread rise
Don't do it.
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Sniff super glue