Oh wow I actually had a showerthought to make a similar topic. Need to brush my wisdom teeth which are all the way at the back of my mouth, and pushing my toothbrush that far activates my gag reflex. Yet I need to brush them because last time I went to the dentist he said everything was good except for my wisdom teeth and that I needed to get in there and brush them. He could tell I was not reaching that far back.
http://i.imgur.com/0UFI0T9.jpg