I've seen some of these before but wonder what you've seen or found ..
Illinois Silly Laws:
The English language is not to be spoken.
You may be arrested for vagrancy if you do not have at least one dollar bill on your person.
You must contact the police before entering the city in an automobile.
You may be convicted of a Class 4 felony offense, punishable by up to three years in state prison, for the crime of "eavesdropping" on your own conversation. -720 ILCS 5/14-2.
And, out great city of Chicago has a few, too ...
It is illegal to give a dog whiskey.
In the Pullman area, it is illegal to drink beer out of a bucket while sitting on the curb.
Law forbids eating in a place that is on fire. (Good idea.

)
Kites may not be flown within the city limits.
It is forbidden to fish while sitting on a giraffe's neck. (This is important)
Spitting is forbidden
It is legal to protest naked in front of city hall as long as you are under seventeen years of age and have legal permits.
Dumb Warnings
On some Swanson frozen dinners: "Serving suggestion: Defrost"