This is great to teach kids how to cite evidence and give reasons in opinion writing in a really fun way! "I have evidence that my dad is an alien" is an Audi commercial that can lead to a great discussion about observations.
I do this each year in my own classroom by giving each student 10 or 12 random hearts (they can swap if they want) and let students write their own Valentine letter based on their heart candies. Kids have loved it for 15 years. lmg