Have you ever been to a party and been caught in a conversation you didn't want to be in? And you can see in the other guest's eyes they don't want to be in the conversation either, however, the other guest is in the middle of some long winded self-important diatribe. You are just politely waiting for them to finish their story or philosphical point, or lame ass joke so that you can execuse yourself to go to the bathroom. But then, before you can get a word in the other guest says, "Yeah, I've got to go the bathroom." Wow! Hold-up. I was going to go the bathroom. I knew this conversation was a tortutious hell, but you were talking. I was being polite letting you finish. For my politeness I get to beg out of the conversation it's my reward for proper awkward conversation etiquette. You've usurped my right to pretend to have to go to the bathroom. If I didn't think I was going get to leave on my terms I would have continued to nod my head in agreement as if I cared about how you forsee your future alcoholism.
And another thing people. If you do leave a conversation with the Bathroom Execuse actually go to the bathroom.