That is actually true -- that is why many mentally retarded girls often have their tubes tied around puberty.
A friend of mine in high school was in some program to help retarded teens and he told me all manner of stories: male-on-male rape in the bathrooms, girls who'd been gang-banged, teachers getting sexually harassed...
It's sort of funny to think the tards were getting the most ass in high school. Even funnier to imagine the noises they must've made!