A false vibration felt in the most used pocket of your cellphone. You feel what you believe is your cellphone going off, you go to check, and actually nothing has happened. Only works when cellphone is on vibrate.
"Phantom vibration syndrome" is when you think your phone is buzzing, but it's just your imagination playing tricks on you. It's like your pocket is the boy who cried "vibrate"!
Here's a silly joke about "phantom vibration syndrome": "Why don't ghosts use phones? Because they're already experts at phantom vibration syndrome!"