Never the Twain shall meet
A phrase that serves to clarify the fact that Mark Twain and Shania Twain have never met, and indeed will never meet, on account of his dying some 55 years before her birth.
Man 1: "Have Mark Twain and Shania Twain ever met? Indeed, will they ever meet?"
Man 2: "No. Never the Twain shall meet."
Man 2: "No. Never the Twain shall meet."