Tell me how long it takes you to break out. You've been warned. You can't stay in them when you want to. It's like the contents are really not there. But yet, you still have to back out of it one frame at a time.
Some websites do it accidentally.
My does it on purpose. The Source Frame Page for this Frame Page had to be typed up at least three times because saving a frame file in NNG completely wipes it out. I'm not even going to try. On second thought, maybe I will, but I'm not going to put a whole lot of faith in it. The Ulimate Crasher - See below.