At ten in the morning, your door bell rings and wakes you up. You hurry to get the door, but when you open the door, you see that you're too late. When you were about to close the door, you see a box on the floor.
You weren't expecting any deliveries, and there weren't any name or address on the box, so you rip open the box with curiosity, there's a black box in it. You take the box, "Magic Headphones" is written on it.
Opening the box, you see there are black headphones with a screen-ish thing on one side (why is that?) and user's manual in it. You love listening to music, so you can't wait to try it. You wonder why is there a user's manual for headphones, so you check it out.
It says "Magic Headphones! Listen to a song with them and your dreams come true!"
You think that it's just a marketing ploy, but you keep reading. Appearantly, while you are listening to a song, and think about something related with the song, it comes true.
For example, if you listen to Animals by Martin Garrix with these, and think about you becoming a dog, you become a dog. Or if a girl listens to If I Were A Boy by Beyoncé, and think about becoming a boy, boom! She becomes a he.
You definitely don't believe in "magic" stuff, but since the headphones looked nice and quality, you decide to give it a shot.