make an embarrassing or foolish mistake - British informal Dropping something that
makes a loud clang attracts attention. This mid 20th-century expression is used especially
in the context of a very embarrrassing or tactless act or remark made in a social situation.
1998 - Spectator - Yet he never escaped from his own nagging suspicion that he had somehow overachieved and that he was likely to drop a huge clanger at any moment.