Good Unix pranks for kids?

[Stefan Scheytt]

Hello fellow monglers,

Due to parental responsibility, we occasional use x11vnc to have a look at
what episode of Hanna Montana our 9-year-old is watching on Youtube today.
(Obviously, we ssh into her machine and sudo to run that program.)

Do you guys know any other fun pranks to play on an unwitting X user from
a privileged command line?

I found xcowsay, but it doesn't seem to work right. Always bones out on the
display issue.

Best Regards,

  - Stefan Mechanic