Partly because it's applicable, but mostly because it is funny.
So a teenage girl asks her dad if she can go see a movie with her friends. He asked her what it was rated and she replied: "It's rated are but one of my friends has already seen it and she says that there are only like 2 bad parts in it and I can just close my eyes for those parts and so it's no big deal."
The dad thinks for a second and then says, "follow me." He goes into the kitchen, pours a glass of OJ and asks his daughter if she like OJ. She does. He takes a teaspoon from the drawer and once again says: "follow me." They go into the bathroom. He takes the teaspoon and scoops up a spoonful of water and puts it into the OJ. Then he hands the glass to his daughter and says:
"Take a drink." The daughter looks at him in disgust and then realizes the point.
"I get it. I won't go."
I just thought it was funny. The highlight of my church going experience for the day.