Is this legal, illegal, or just fucked up?
“American Airlines, can I help you?
“Hello, this is Allahu Akbar al Jihadi. There is no bomb aboard Flight 2257 from Paris. Repeat–no bomb.”
“No bomb?”
“No. None. You can relax. And on Flight 4141 from Miami–those guys are not hijackers.”
“Not hijackers?”
“No, they’re day laborers. The hijackers got scared on the way to the airport and hired them instead. Unfortunately, they’re quite harmless… But whatever you do, for God’s sake don’t let them drink too much. Tell them you’re flying over a dry county when they ask for seconds.”
“Ok…anything else?”
“Yeah, could I get a one-way to Isantbul tomorrow?”
Perverted Wisdom 
Its totally illegal
What about the first part of the joke–just calling an airline or a building and telling them that there is NO bomb in plane/building? Is that illegal?
It not but its sound as if there really is a bomb in the plane since it was not your duty to report such in the first place. Its what my people call expensive jokes