Don’t want to hurt anyone but love to cause a needless stir? Try leaving things that look explosive — but aren’t — in public view.

On Sunday, a “suspicious device” was spotted at a Catonsville apartment building; police were called in; and the building was evacuated. Turns out there was good reason for the suspicion — the object was in fact a grenade, albeit an inert one, no longer capable of exploding.

Maybe something’s going around, because last week, a similar pandemonium machine brought a bomb squad to Fairfax County, Va., shutting down traffic.