Is a stop sign on the back of an ice cream truck a real stop sign that has to be obeyed? When did they start putting these signs on ice cream trucks?
My WAG is that since a stop sign is a regulatory traffic sign maintained by the state, any other use by a private company is without state authority, i.e., it’s not legal and you do not have to obey it.
However, since state laws vary, and you did not provide which state you live in, there is really no way to check the state laws to determine a factual answer.
It’s Homer J. Simpson. He live in the state that Springfield is in. 
Thanks, adam, you just got this thread thrown into Great Debates 
Well, the state I live in is unimportant. I was in Illinois, while I live in
In New York I’ve only seen yellow signs that read “SLOW”. Sometimes they read “SLOW CHILDREN”, but ice-cream vendors with such little regard for their demographic I have no use for.
Seriously, ice-cream truck with red, octoganal STOP signs? I seriously doubt any cop would ticket you for passing one, but check your local statutes.
I know stop signs on school buses are enforcable, at least in my state. I don’t know about ice cream trucks, or for that matter crossing guards (although presumably in that case one is required to stop anyway).
State law may vary, but in NJ, ice cream trucks share similar privileges as school buses. The stop signs are legal and must be obeyed. Only, with the ice cream trucks, you can pass after a full stop, not so with school buses.
Peace.
Now, only if funeral directors can get children to come running up to the hearse, maybe they can finally get right of way privileges…
My WAG would be that while you may not be obligated to obey the sign itself, there are likely other safety laws which apply to ice cream trucks, school buses, and the like.