If you happen to have a Samsung cell phone* you can now turn it into a vibrator.  Sexy ƒrequency provide this tip/trick for information purposes only and accept no liability for a broken phone.

To access the vibrator controls, enter the following number into your keypad:
*#9998*VIB#
*#9998*842#

This should bring up a vibrator control menu.  e.g.
[1] On/Off
[2] Always on
[3] Off
[*] Exit

* Doesn't work on every Samsung phone.

Have fun.