Nobody knows for sure, but could be defined as the insides of ones genitalia. Denis Leary coined this word but never quite says what it is. Most think it is just best left to the imagination, because when it is, it conjures up images of everything unappetizing with the human body.
Person 1-Hey, look at that woman over there shes hideous
Person 2-I dare you to ask her for a good hard look at her subcockles..
Person 1-Well i can already see them.