You're on a bus.
You can hear very loud music.
You're drinking your second can of Mountain Dew.
All of a sudden, you realize that you really need to burp.
You think about the situation and decide that maybe, just maybe, you could burp on the beat and the loud music would disguise the sound.
So you try it.
You are impressed with your creativity and problem-solving skills.
Then you get off the bus... but the music still follows you.
You realize you've been listening to your iPod.