S -> "A man", "a plan", (NP,)* "a canal, Panama!"
which I suppose you could call a sentence.
You guys know the Weird Al song, right?
http://www.youtube.com/watch?v=Nej4xJe4Tdg
http://everything2.com/index.pl?node_id=830538
I'd be glad to find longer ones!
S -> "A man", "a plan", (NP,)* "a canal, Panama!"
which I suppose you could call a sentence.