(Please keep in mind that this conversation transpired at the dinner table, where grandpa was most assuredly present.)
Liz: "Why do green beans squeak when they rub together?"
Mom: "I don't know... Maybe it's because they are excited."
Liz: [Laughs] "They are excited?"
Mom: "Yeah, don't you get excited when you rub yourself on something?"
Liz: "That entirely depends on what it is that I'm supposedly rubbing myself on."