Perry....you wanna take this one??
......hornykid, you must really be a kid....anybody over the age of 30 knows what their prostate is.....
Anyway....your prostate is the gland that supplies the fluid which makes up the most of your ejaculation(sperm being the other component). Prostate's can cause all sorts of health problems for men as they age....cancer being the "biggie". Your doctor will check for cancer by inserting a gloved finger up your rectum and feeling for lumps, changes in surface texture, and for englargement.
Prostate massage, when you have an erection, and are being masturbated, produces much more ejaculate, than just a normal orgasm.
Some of the boys find this pleasurable, and there are health benefits as well.
Google "prostate" and "prostate massage".....probably over 100,000 hits...