If you have access to a two(or more) line phone, this is a great one,

If you have access to a two(or more) line phone, this is a great one,
dial the first six numbers of your prey's phone number, and put that line on
hold, then dial the other number; a pizza place, or his girlfriend is good for
starters, then escalate to college offices, activist terrorist organizations
and the CIA are good from then on. After you dial the second number, quickly
put the second number on hold, then dial the last number of the first number
and push BOTH buttons down at the same time to activate both calls at once,
then listen, but don't laugh, or they might hear you and do worse in return.