One of the main male sphincter muscles is located between a mans testicles and anus.
It is a very important muscle as it looks after urination, defecation and ejaculation.
If any of the above are causing problems then that sphincter muscle needs to be exercised.
In order to exercise this muscle then just try to push your penis fer a pretend wee or stop it or just try moving your penis without touching it, this will trigger the sphincter muscle and exercise it.
EXTREME CAUTION is advised in exercising this sphincter, as over-exercising can give ya aches and pains where ya really don't want em.
Try lying in bed and exercise the sphincter about Ten times per night fer the first week, increasing to 15 the week after and then up to 20 and maybe even 25 after that. (It takes all of about One minute per night).
You will see an increase in your control of all 3 of urination, defecation and ejaculation once that sphincter muscle is properly exercised.
Again EXTREME CAUTION, Do not over-exercise !