https://en.wikipedia.org/wiki/Prostate_massage
Maybe can DIY if cannot find prostate milker
Electroejaculation is a procedure in which nerves are stimulated via an electric probe, which is inserted into the rectum adjacent to the prostate. The stimulus voltage stimulates nearby nerves, resulting in contraction of the pelvic muscles and ejaculation. It is most commonly encountered in animal husbandry for the purpose of collecting semen samples for testing or breeding. Some devices are used under general anesthesia on humans who have certain types of anejaculation.[10] Electroejaculation is a different procedure from manual prostate massage.