There are fish that habitually eat which are eaten by fish that are in turn eaten by other fish. So, fish eat. Even fish [that] fish eat [have to] eat. And fish eat fish that eat fish that eat.

Also try it with varying nouns and verbs: Mice cats dogs chase eat sleep. (Dogs chase cats that eat mice that sleep.)

I like it because it seems to exploit a very low maximum stack depth in human sentence parsing.