When the sink backs up its a bad idea to think that its not a big deal.
Fast forward to us 'snaking' the drain until midnight (if we didn't go to the aquarium first we would have probably given up a little earlier), since that didn't work we called Rob the plumber. He got the big guns out and cleared the clog. The fun really started when he was backing out the industrial sized snake and we heard flopping around inside the wall. Turns out there was a hole in the pipe. Its old, its rusty but not no more.