The phrase what have I done is a familiar piece of everyday English, used in drama, comedy and real life whenever someone recognises a serious mistake. As a short standalone clip, it has become a handy reaction sound online because the meaning is clear even without context, subtitles or a familiar character. Creators reuse it for fail compilations, gaming mishaps, prank fallout and storytime edits, where a single regretful line can carry the whole joke. Its staying power comes from that instant readability: anyone who has made a bad call recognises the feeling immediately.