a humorous way of writing the phrase ‘I’ve got you!’, which a person says when they have found or caught somebody, or when they win an argument. Many people were shocked when it was used as the headline of the Sun newspaper with a picture of an Argentinian ship after it had been badly hit by guns fired from British ships during the Falklands War .
GOTCHA!
Meaning of GOTCHA! in English
Oxford guide to British and American culture English vocabulary. Руководство по британской и американской культуре, Оксфордский английский словарь. 2005