for goodness’ sakes/for goodness’ sake: Common Errors in English Usage Entry for Thursday, April 25, 2013

for goodness’ sakes/for goodness’ sake
Picky folks point out that since the mild expletive “for goodness’ sake” is a euphemism for “for God’s sake” the second word should not be pluralized to “sakes”; but heavens to Betsy, if little things like that are going to bother you, you’ll have your dander up all the time.