Whilst searching for pornagraphic material in preperation for a worth while masturbation session, one clicks upon a site described as 'blonde gets gangbanged by three well hung men'. Once clicked upon said website reveals itself to be an old granny being set upon by three midgets. This instantly kills the mood (for any well adjusted person) and is known as hitting a 'wank mine'.
Searching for porn and finding out the 'beautiful blonde with big naturals' is in fact your mother. My friend, you have just encountered a 'wank mine'.