George Washington slept here

A phrase used to mock or convey doubt of a claim. The New York Times puts it as “a common punch line for dubious historical claims.” The phrase’s infamy originated from the sheer amount of such signs in colonial places used to advertise and get people’s attention.

There is also a Brodway show and movie called “George Wasnington Slept Here,” the name a reference to this phrase.

“Did you know Shakespeare invented the letter Q?”
“Yeah, sure, and George Washington slept here.”