On a highway in New York, "Caution, state correctional facility ahead, do not pick up hitchhikers."

I saw a sign yesterday that read "No Outlet", right under it was a tiny sign that said "one block ahead."

A sign outside a furniture store in northern Virginia states (in large letters)
"ANTIQUE Tables Made Here Daily."

On a trip to London, we visited a museum which had special facilities for disabled visitors. Many exhibits had small brass plates with Braille writing (you know, with raised dots so blind people can 'feel' the words). The translation underneath said, "PLEASE DO NOT TOUCH THIS EXHIBIT."