a police officer pulls over a nun driving a car and says "maam, you're driving too slow, could you please drive faster?" the nun says, "oh, i saw the sign with the '21' and assumed the speed limit was 21." the officer explains "no maam, the speed limit is 65, the highway is 21."

then the officer looks in the back and sees the other two nuns shaking like leaves. "excuse me, sister, but what's wrong with those two?" "oh, thats because we just got off highway 145."