They were bright orange with the words LITTER BUG printed in large white upper-case letters on the lid, along with a large white arrow pointing inside, and had a circular cover that pivoted open by one edge of the lid. The name refers to litterbugs, a slang term used since the late 1940s for people who throw their trash on the ground in public.
In contrast to the usual meaning, the Litter Bug actually helped discourage people from littering, listening for anyone to mention they want to throw something away, moving close to them, and opening its lid in readiness.
On October 21, one of these mobile trashcans almost knocked Emmett Brown over as he was looking for somewhere to dispose of the Grays Sports Almanac which Marty McFly had bought from the Blast from the Past antique/memorabilia store. However, Doc was distracted by the arrival of Officers Reese and Foley, who had recovered Jennifer Parker in the alleyway, and so didn't make use of the Litter Bug while it was there — throwing the almanac into a more traditional stationary trashcan instead, where it was found shortly after by Biff Tannen.
- Robotic mobile trashcans like the Litter Bug featured in Back to the Future Part II have yet to appear on the streets of America.