Never heard of that. Sounds pointless.
To force-quit any app as standard just hold down the home button while you're in the app you want to quit. It will close itself after a few seconds and wont be running in the background.
Alternatively, if you're jailbroken there are a number of third party apps that can show you what's running in the background and quit them too.
Kirikae and MemInfo are 2 I know of and use on a regular basis. (Both available from Cydia)