Am I really that unreasonable to get a little narked by that turn of phrase and think its only used by really, really pious people? The sort of people who on hearing you are pregnant ask whether the child was planned before offering congratulations.
And the 
face and bemused really face, if you say "yes, I was taking it properly, yes I am aware some medications affect it".
BTW I am not horribly offended by people saying this,just as I said narked. It says on any literature you get with any contraception that it may fail. And secretly I believe failure statistics are a lot higher than those quoted on the packet
AIBU to correct the phrase to "There is no excuse for unplanned pregnancy as long as you stay at least 10 foot away from any uncontrolled sperms", next time I hear this helpful nugget of wisdom?