Dan: "Leroy, you have such terrible breath. It smells like you pooped a fish and then ate it."
Dan: "Wait, does a vertical line have a slope?"
Me: (with certainty) "Yes, a vertical line has a slope of one. A horizontal line has a slope of zero. A vertical line has a slope of one."
Dan: "Are you SURE?"
Me: "Yes! A vertical line has a---"
Dan: "--slope that's undefined. It's undefined."
Me: "You're totally right. You're right and I am insane. And I am in charge of homeschooling your children."
Dan: "Yeah, thank goodness they make books."
RIGHT DAN. Thank goodness for THEM and those BOOKS they make.