Just behind the balls is the perineum, not prostate gland. The prostate gland is stimulated through anal play. You can feel it through the wall of the rectum and rub it gently. So while it is not in your butt or the butt, you stimulate it through the butt.
Google: locating prostate stimulation
http://www.prostate-stimulation.com/
Main Entry: per·i·ne·um
Pronunciation: "per-&-'nE-&m
Function: noun
Inflected Form(s): plural per·i·nea /-'nE-&/
Etymology: Middle English, from Late Latin perinaion, from Greek, from peri- + inan to empty out; perhaps akin to Sanskrit isnAti he sets in motion
Date: 15th century
: an area of tissue that marks externally the approximate boundary of the outlet of the pelvis and gives passage to the urinogenital ducts and rectum; also : the area between the anus and the posterior part of the external genitalia
Main Entry: prostate gland
Function: noun
Date: 1828
: a firm partly muscular partly glandular body that is situated about the base of the mammalian male urethra and secretes an alkaline viscid fluid which is a major constituent of the ejaculatory fluid
Please note: there is a difference between
prostate gland and
prostrate.
Main Entry: 1pros·trate
Pronunciation: 'prä-"strAt
Function: adjective
Etymology: Middle English prostrat, from Latin prostratus, past participle of prosternere, from pro- before + sternere to spread out, throw down -- more at STREW
Date: 14th century
1 : stretched out with face on the ground in adoration or submission; also : lying flat
2 : completely overcome and lacking vitality, will, or power to rise <was prostrate from the heat>
3 : trailing on the ground : PROCUMBENT <prostrate shrub>
synonym see PRONE