The phrase "fake bomb" refers to something that looks like a bomb but is not made to explode or cause harm. It is usually created for a prank or for training purposes, like in movies or drills. Full definition
You can be charged with disorderly conduct for calling in fake bomb threats, falsely reporting the presence of a gun, or falsely reporting threats of violence against a student or teacher. (kostlaw.com)
A former journalist pleaded guilty to cyberstalking and making fake bomb threats, admitting he threatened Jewish organizations to disrupt his ex-girlfriend's life and cause her «great distress.» (nystateofpolitics.com)
Oklahoma's News Channel 4 NE Oklahoma City shooting leaves two dead; Vehicle fire shuts down I - 240; Suspect on the run after leaving fake bomb at metro Watch your favourite shows online, from Channel 4, E4, All 4 and Walter Presents (myintimcity.com)