The prostate also known as the "A-Spot" is the male G- Spot. Stimulation of the prostate can be done by applying external pressure on the perineum (area between the anus and testicles) or directly to the prostate.
Many men, heterosexual and homosexual, enjoy anal stimulation due to the increased sensation and stronger ejaculation. You are also more likely to have an orgasms, not just ejaculate, as a result of prostate stimulation.