Traffic signs that scold

[Duke87]

^ Is this meant to warn of a 6% downgrade of a 6-mile length?

Yes, and you're right, the wording is potentially unclear. I understood it perfectly but then I knew what was coming despite having never driven it before because roadgeek.

[Pete from Boston]

The old Breezewood "You slow down" sign.

And then you have Colorado.

Quite a few there, including

[hm insulators]

How about "illegal to leave highway to avoid traffic signal" from EB 75th Street at IL 53 in DuPage County?  Streetview

There's a similar sign in Flagstaff, Arizona on old Route 66.

[US71]

Used to be a sign along US 71 at Winslow, Arkansas

10PEOPLE KILLED IN THE LAST 3 YEARS
DON'T YOU BE NEXT.

Of course, MoDOT is notorious for the "NAG"  VMS's.