On a similar vein (fnar) a pal of mine who'd encountered the age old phenomenon when you find that the time you most definitely need one of your little rubber life - and bank balance - savers there were none to be found.
I'll repost a (true) story I submitted to B3ta.com a couple of weeks back:
Just for the record, I wouldn't stoop THIS low.
"Have you, erm got anything?" breathed his newest prospective squeeze when things began to take a passionate turn.
"Not sure, but I'll have a look" answers the gentleman in question knowing full well he's out of rubber.
Now I like to think that if I were in his position, I'd fess up and say "Not tonight Josephine, let's just hold each other like two chaste lovers and discuss poetry instead" safe in the knowledge that I'm being a gentleman and that no local all night pharmacy is within sprinting distance.
Our hero simply retires to the bathroom and draws a biro line round his old boy, before returning to the dimly lit boudoir and announcing "Ooh, I found one".
sincere apologies to la Blob for subverting her post!