“For fuck sakes”, The person has annoyed you enough to become the fuck given.
“For fucks sakes” suggests that many fucks are now given, taken or forsaken and the person should shut the fuck up.
“For fuck sakes”, The person has annoyed you enough to become the fuck given.
“For fucks sakes” suggests that many fucks are now given, taken or forsaken and the person should shut the fuck up.