It's definitely one of the more extreme methods of contracepetion, but scientists suggest that in the future, blasting a man's sensitive area with high frequency sound waves may be the ideal form of contraception.
Just try and get them in the chair first.
They found that 15 minutes of ultrasound on rats reduced their sperm count to levels that would mean infertility in men.
But researchers say they do not yet know how long the ultrasound would work nor whether it is safe to be repeated.
Study leader Dr James Tsuruta. from the University of North Carolina, said: "Unlike humans, rats remain fertile even with extremely low sperm counts.
"However, our non-invasice ultrasound treatment reduced sperm reserves in rats far below levels normally seen in fertile men.
"Further studies are required to determine how long the contraceptive effective lasts and if it is safe to use multiple times."
A cheap, effective non-invasive male contraceptive has been a goal of scientists.