Okay, here's a pretty bad one.

Three people schedule an afternoon to have lunch together in a hot air balloon. After leaving, they wait a little while before opening their lunches.

The first person opens his lunch and finds a sharp knife. He doesn't need it, so he throws it out the balloon.

The second person opens his lunch and finds a sharp knife. He doesn't need it, so he throws it out the balloon.

The third person opens his lunch and finds a ticking bomb, so he chucks it out the balloon as fast as he can.

Later, they finish and return to their homes. The first person comes home and finds his mom crying. He asks what's wrong. She replies "Your father was killed this afternoon. A knife fell from the sky and killed him."

The second person comes home and finds his father crying. He asks what's wrong. The father replies "Your mother was killed this afternoon. A knife fell from the sky and killed her."

The third person comes home and finds his dad laughing on the couch. He asks what's so funny. The dad replies "I farted and the house next door blew up!"