A computer program used in tandem with a small semispherical grey robot called a "walker". Users would enter commands into the computer, and using the magic of technology, the little grey shit would bleep and draw a sqaure on the ground.

The fun, however, usually came with typing in the commands. It only understood simple words such as "move" and "right". Any other instruction would be greeted with "I do not know how to X". Being 7 years old, this was BRILLIANT:

"I do not know how to fart"
"I do not know how to smell"
"I do not know how to boobies"