Though not associated, there are two businesses in the United States that go by the name "Retardville". One's a stationery in Kingston, Pennsylvania. The other is a education staff member in Louisville, Kentucky. If someone accuses you of saying an offensive slur, go to bizarchive.com and prove it's a location. If they remain angry, ask them which one they work at.
I was a former teacher for little kids at Retardville. I had a lot of trouble engaging them, so I moved on to an easier job.