BonziBuddy? is rumoured to be the evil spawn of some incarnation of TheDevil? . . .

It's evil, it's purple, and it's a FRICKIN' MONKEY! . . . That monkey . . .

Once installed it infests your computer and hijacks your desktop, it latches its invisible TentaclesOfEvil? into wherever it can, and the only way to rid yourself of its sickness is to replace your hard disk. (Some say reinstalling your OperatingSystem is sufficient, but you never can be sure . . .)

See Spyware? for more information (including how to get rid of it)

Sometimes used as a practical joke against workmates, however this can be likened to killing your workmates first born so use at your own peril.