Recursion: If you get the point, stop, else see ReCursion.
(also see InfiniteRecursion)
http://xkcd.org/446 (see the title text...)
In computer programming, recursion is when a function calls itself in the process of accomplishing it's task.
Or consider listening. Say you have a friend who's struggling with something and you want to help by listening, but you have so many things going on in your own life that you're not sure you could listen well. You might first spend some time getting someone else to listen to you for a while.
Great list of self-referential sentences:
http://www2.vo.lu/homepages/phahn/humor/self_ref.htm
See ScienceAndTechnology, SecondOrderCybernetics, OpenSpaceOnOpenSpace