A type of red swelling of the anus, as a result of over-use of anal insertions (through sexual intercourse, or foreign objects of increasing girth) The over-use of such activity leads to the person's anus being perminently red and swollen, and leaves it in a state of constant "gaping", with the sphincter glad unable to operate properly due to constant abuse. This can cause the recipient long term issues with boewel control.
The act of "anal destruction" is popular in certain homosexual groups.
Name is based on the "hind" becoming soft and wet, like a "marsh"
Did you see Lee, in the shower? He's got a serious case of the Hindmarsh hernia