The Chinese jester Zhu Hanzhen 祝漢貞 (Wish Upright Fellow) – whose name seems to have been counter to his character as he was later beaten and banished for accepting a bribe – served several emperors with his great humour and an ability to trip seven-characters-per-line poems off the tongue at a moment’s notice.
When the emperor’s attention was caught by something, he would ‘suddenly order him to come up with a poem about it which he would do quick as a flash, as though he already had one up his sleeve, which particularly delighted the emperor’.
Source: Tang yulin 唐語林, by Wang Dang 王讜 (fl.c. 1110), fol. 2, Siku Quanshu 四庫全書 (Shanghai: Guji Chubanshe, 1987), vol. 1038, p. 28b.