Confuse traffic signs

A cop pulls over a carload of nuns.
Cop: "Sister, this is a 65 MPH highway -- why are you going so slow?"
Sister: "Sir, I saw a lot of signs that said 22, not 65."
Cop: "Oh sister, that's not the speed limit, that's the name of the highway you're on!
Sister: Oh! Silly me! Thanks for letting me know. I'll be more careful.
At this point the cop looks in the backseat where the other nuns are shaking and trembling.
Cop: Excuse me, Sister, what's wrong with your friends back there? They're shaking something terrible.
Sister: Oh, we just got off of highway 119.