a situation which you can not deal with, (cannot remove or shove in the saw 'coz either ways your ass is torn) or leave it as it is...
a situation in which no matter what you do you are fucked...
do and die, don't do and still die situation...
A saying that you use when you, or someone else, are at or just had an all time low moment. The emotional or physical pain is compared to being fucked in the ass. Not only is life treating you unjustifiably bad, it is also going to great lengths of emotional or physical destruction.
Bob: My girlfriend just told me there was someone else. Yesterday, I asked her dad for permission to marry her.
Jim: Life Is A Bitch And Sometimes It Fucks You In The Ass.