They shouldn't -- if they do, they're too tight and will cause injury.
Not completely, no. They do, however, make erections last longer so can be popular from men who suffer from premature ejaculation. Testicle cuffs have the same effect, as well as holding the scrotum away from the body, which can change and intensify the feeling of orgasm.
The man ejactulates about 30 million or so sperm per ejaculation
Sperm can be found in testicles, or semen after ejaculation (with other fluids).
It is believed that regular ejaculation does help to prevent prostate cancer.
An orchiectomy is sometimes done to prevent cancer when an undescended testicle is found in a patient who is beyond the age of puberty.
You cannot, don't try it, if you want to prevent it don't reach you climax.
One of the most common is the "squeeze technique" to prevent premature ejaculation.
cuffs
In most cases the doctors would put a 'falsie' in the scrotum. As long as the other testicle is healthy, it would not prevent reproduction.
stoping for a short Tim should work. and ther are myths of if you yank your balls down that should work
cuffs is the best answer that I could think of
French cuffs are folded-back cuffs on a dress shirt that are longer than regular cuffs, typically requiring cufflinks to fasten them together. They add a more formal and stylish touch to a shirt, making them perfect for more sophisticated occasions.