Originally Posted by Tarek Morgen

I have an example for "accidental affair".

Some years ago I was camping with a larger groups of friends and most of us had brought their girlfriends. During the night at the campfire most consumed quite an amount of beer, and when one of the boys wanted to join his girlfriend who was already in the tent. darkness and alcohol combined somehow let him to the wrong tent were the wrong girl waited (for her boyfriend) and it was not until he asked confused "Did you breast get smaller?" they noticed the mistake. At least the guy has never drunk a single beer since then (and he is bavarian)