Greyhound has scrapped a billboard ad campaign that extols the relaxing upside of bus travel in the wake of a bus attack in Canada where a man beheaded and cannibalized another passenger.

The ad's punch line was "There's a reason you've never heard of 'bus rage.'"

Greyhound spokeswoman Abby Wambaugh said Wednesday two of the billboards are still up but that they want them removed as quickly as possible.