NEVER on the plane!

After a month-long holiday in the US, my wife and I finally boarded the
plane in San Francisco last Sunday heading home.
As the plane reached cruising speed with the seat belt sign switched off, a
6 ft 3" black man with the build of Mike Tyson in the front row got up from
his seat, turned to face the back, raised his arm and yelled, "HIJACK!"
Everyone was frozen to the seat, expecting the worst to happen. And two
stewards were about to jump onto this guy to overpower him when another
voice answered from the back of the plane:
"HI JOHN!"
The moral of the story is: If you have a friend named Jack, for heaven's
sake don't ever call him on the plane. Otherwise you may land yourself in
deep shit.