From 韩愈《祭柳子厚文》: '玉佩琼琚，大放厥词' — originally neutral/praiseful, describing Liu Zongyuan's free-flowing eloquence. In modern use the meaning has flipped to derogatory: empty talk or boasting.
mistakes
厥 here is a classical possessive pronoun equivalent to 其 ('his/its'), not the medical 厥 (to faint).
