Mobile phone
Is a phone that you can carry around, at the cost of making you impotent, risking blowing up gas stations, screwing up your pacemaker if you have an abnormal heart, screwing up your heart if you don't have a pacemaker, causing brain cancer, thumbscrew, increases the number of your specs, ruins your actual social life...
But it has a built in vibrator.
But it has a built in vibrator.