Star Trek: The Original Series, Season 1

Kirk:
This is the Captain of the Enterprise. Our respect for other life forms requires that we give you this... warning. There is one critical item of information that has never been incorporated into the memory banks of any Earth ship. Since the early years of space exploration, Earth vessels have had incorporated into them a substance known as... corbomite. It is a material and a device which prevents attack on us. If any destructive energy touches our vessel, a reverse reaction of equal strength is created, destroying --

Balok:
You now have two minutes.

Kirk:
-- destroying the attacker. It may interest you to know that since the initial use of corbomite more than two of our centuries ago, no attacking vessel has survived the attempt. Death has... little meaning to us. If it has none to you -- then attack us now. We grow annoyed at your foolishness.