Quote from Lorelai in Written in the Stars
Lorelai: Okay, but think about it. Why do we need the word "potty"? Is it really that much harder for a kid to learn the word "bathroom"?
Rory: I don't know.
Lorelai: "Timmy, do you have to go potty?" Or "Timmy, do you have to go to the bathroom?" See? Interchangeable.
Rory: Not exactly interchangeable.
Lorelai: How are they not interchangeable?
Rory: To go potty is an action. To go to the bathroom is to go into a specific place.
Lorelai: And I hate the word "potty."
Rory: Well, what did you teach me to say?
Rory: You did?
Lorelai: Yes, of course.
Rory: I'm 2, I come up to you and I say, "Mommy, Mommy, I have to go to the..."
Lorelai: The room where legends die.