SYDNEY, Australia (Reuters) — An Australian bus driver who called police after he found a package on his bus which emitted a strange sound when touched was left red-faced when it turned out to be a novelty store cushion.

Just two weeks ago Sydney, Australia's largest city, adopted a New York-style "If you see something, say something" counter-terrorism campaign urging people to report unattended bags or suspicious activity around public transport.

The driver found the package on the rear seat of his bus after completing his route around the Sydney beachside of Coogee on Sunday.

Fearing it could be an explosive device of some kind, he called the police."It was an unattended item, emitting a popping sound," a police spokesman said.

But when the police went in, they found out it was just a Whoopie Cushion.

In case you live on Mars, the Whoopie Cushion emulates the sound of...ahem...breaking wind — a chemical weapon used most extensively by teenage boys and participants of chili cookoffs.