My quote for today is
Colorless green ideas sleep furiouslyNoam Chomsky
It’s an example for a syntactically valid sentence without any useful semantic.
See wikipedia for detailed information and don’t miss the article about “Buﬀalo buﬀalo Buﬀalo buﬀalo buﬀalo buﬀalo Buﬀalo buﬀalo” – a arbitrary long and syntactically correct sentence constructed of a single word. Limited semantic, though.