gotcha!
1
used as a humorous exclamation of a verbal conquest of some sort. Often used as the gloating afterword when a practical joke is played. On 2nd May 1982, during the Falklands war, the Argentine ship Belgrano was torpedoed by the Royal Navy as she sailed away from the exclusion zone. At least 386 lives were lost. The Sun newspaper printed the notorious, gloating one-word headline: 'GOTCHA'. Also used in triumph when a capture or victory has been achieved UK, 1932.
2
used for registering an understanding of what someone has said. A slovening of '[I] got you' UK, 1966