What exactly is a 'rapid charger' for a cell phone, and why do people ask for it

[Seeker2008]

so much? I work in a retail store in an airport, so we are sort of a phone charger hub for everyone who loses/leaves their cell phones at home/in their luggage. I frequently get the question of if we carry "rapid chargers"...and to my knowledge, there is no such thing as rapidly charging a battery beyond it's capacity of being safely charged. It would be quite dangerous and also bad on the battery, I would think.

Can anyone explain?